I Corinthians 5, Outside vs. Inside

Paul has been confronting the arrogance of the Corinthian church, as they fight about leadership and standing.  In this chapter, Paul addresses the question, "When is it appropriate to discipline another for immoral or unethical behavior?" At one level, the answer is easy....

1 Corinthians 5: 1-5, Incest in the Church

It is actually reported that there is sexual immorality among you, and of a kind that does not occur even among pagans: A man has his father's wife.  And you are proud! Shouldn't you rather have been filled with grief and have put out of your fellowship the man who did this? 

Even though I am not physically present, I am with you in spirit. And I have already passed judgment on the one who did this, just as if I were present. When you are assembled in the name of our Lord Jesus and I am with you in spirit, and the power of our Lord Jesus is present, hand this man over to Satan, so that the sinful nature may be destroyed and his spirit saved on the day of the Lord.

The church, arrogant and divisive, has at the same time been ignoring an active sexual relationship among members that all recognize as wrong and damaging. Paul confronts this harshly.

1 Corinthians 5: 6-8, The new bread of Christ

Your boasting is not good. Don't you know that a little yeast works through the whole batch of dough?  Get rid of the old yeast that you may be a new batch without yeast--as you really are. For Christ, our Passover lamb, has been sacrificed. Therefore let us keep the Festival, not with the old yeast, the yeast of malice and wickedness, but with bread without yeast, the bread of sincerity and truth.

Replace boasting by sincerity.  Remember the Lamb who was sacrificed for us, in sincerity and truth. (Paul's metaphors are strongly influenced by his Jewishness, even if his audience is not Jewish.)

1 Corinthians 5: 9-13, Outside vs. inside

I have written you in my letter not to associate with sexually immoral people-- not at all meaning the people of this world who are immoral, or the greedy and swindlers, or idolaters. In that case you would have to leave this world.  But now I am writing you that you must not associate with anyone who calls himself a brother but is sexually immoral or greedy, an idolater or a slanderer, a drunkard or a swindler. With such a man do not even eat.

What business is it of mine to judge those outside the church? Are you not to judge those inside?  God will judge those outside. "Expel the wicked man from among you."

Paul mentions an earlier letter, now lost.  He also gives clear advice, often forgotten by the Church. Those of us who voluntarily join the church community, who seek to follow Christ, offer ourselves for (constructive) criticism and judgment.  In that realm, (compassionate) judgment is appropriate and may even lead to discipline. But don't judge those who are outside the church!  

If only Christians in America practiced this...!  Instead (in my experience) the church gets this backwards, making pronouncements about those outside the church while often ignoring the sin and hypocrisy within the church!

The Old Testament quote in verse 13 is appears as a common refrain throughout Deuteronomy, see for example, Deuteronomy 17:7; 19:19; 21:21; 22:21,24; 24:7.

I Corinthians 4, True Leadership

Paul has been attacking the divisions within the church in Corinth.

1 Corinthians 4:1-5, It is the Lord we serve
So then, men ought to regard us as servants of Christ and as those entrusted with the secret things of God. Now it is required that those who have been given a trust must prove faithful.  I care very little if I am judged by you or by any human court; indeed, I do not even judge myself. My conscience is clear, but that does not make me innocent. It is the Lord who judges me.

Therefore judge nothing before the appointed time; wait till the Lord comes. He will bring to light what is hidden in darkness and will expose the motives of men's hearts. At that time each will receive his praise from God.

Good advice: don't judge; leave that to God.  Judging others is generally not in our realm of responsibility.  Even one's conscience is not a good judge.

Meanwhile, Paul wishes for the Corinthians to respect and value (but not worship) their leaders like Apollos, Peter and, yes, Paul.

1 Corinthians 4:6-9, You are rich kings!
Now, brothers, I have applied these things to myself and Apollos for your benefit, so that you may learn from us the meaning of the saying, "Do not go beyond what is written." Then you will not take pride in one man over against another. For who makes you different from anyone else? What do you have that you did not receive? And if you did receive it, why do you boast as though you did not?

Already you have all you want! Already you have become rich! You have become kings--and that without us! How I wish that you really had become kings so that we might be kings with you! For it seems to me that God has put us apostles on display at the end of the procession, like men condemned to die in the arena. We have been made a spectacle to the whole universe, to angels as well as to men.

Those apostles (such as Paul, Apollos, Peter) have endured much for the Gospel.  The people in the church in Corinth have received many gifts; they have many strengths and talents.  They need to include humility among their characteristics!

1 Corinthians 4:10-13, We are suffered -- for you!
We are fools for Christ, but you are so wise in Christ! We are weak, but you are strong! You are honored, we are dishonored! To this very hour we go hungry and thirsty, we are in rags, we are brutally treated, we are homeless. We work hard with our own hands. When we are cursed, we bless; when we are persecuted, we endure it; when we are slandered, we answer kindly. Up to this moment we have become the scum of the earth, the refuse of the world.

It is humility and service that are the hallmarks of leadership.  The Gospel of Christ inverts the social pecking order and Paul reminds the Corinthians of this.  In describing the servanthood of the apostles, he is asking the Corinthians to follow that model.

1 Corinthians 4:14-17, I was your father in the gospel
I am not writing this to shame you, but to warn you, as my dear children.

Even though you have ten thousand guardians in Christ, you do not have many fathers, for in Christ Jesus I became your father through the gospel. Therefore I urge you to imitate me.

For this reason I am sending to you Timothy, my son whom I love, who is faithful in the Lord. He will remind you of my way of life in Christ Jesus, which agrees with what I teach everywhere in every church.

Paul now is explicit in his insistence that the believers in Corinth imitate his service and stresses this by assigning Timothy to travel there and help monitor church development and growth.

1 Corinthians 4:18-21, Spiritual power, not talk!
Some of you have become arrogant, as if I were not coming to you. But I will come to you very soon, if the Lord is willing, and then I will find out not only how these arrogant people are talking, but what power they have. For the kingdom of God is not a matter of talk but of power.

What do you prefer? Shall I come to you with a whip, or in love and with a gentle spirit?

Paul wants Timothy's visit to be one of love and support, but he oscillates between frustration and optimism.  He asks the Corinthians to make a decision.  

The difficulties the Corinthians face will be explored in the next chapter.  Paul will elaborate on when it is appropriate to condemn another's behavior.

I Corinthians 3, Building an Eternal Church

Paul continues to talk about the spirit-led life and to attack the divisiveness of the Corinthians.

1 Corinthians 3:1-4, Jealousy
Brothers, I could not address you as spiritual but as worldly--mere infants in Christ. I gave you milk, not solid food, for you were not yet ready for it. Indeed, you are still not ready.  You are still worldly. For since there is jealousy and quarreling among you, are you not worldly? Are you not acting like mere men? For when one says, "I follow Paul," and another, "I follow Apollos," are you not mere men?

What makes the Corinthians immature?  Their jealousy and quarreling.

1 Corinthians 3:5-9, We work together in one purpose
What, after all, is Apollos? And what is Paul? Only servants, through whom you came to believe--as the Lord has assigned to each his task. I planted the seed, Apollos watered it, but God made it grow. So neither he who plants nor he who waters is anything, but only God, who makes things grow.

The man who plants and the man who waters have one purpose, and each will be rewarded according to his own labor.  For we are God's fellow workers; you are God's field, God's building.

The believers in the city of Corinth have allied themselves with various leaders and apostles, forming sects.  Paul confronts the division, arguing that whether they were discipled by Paul, Apollos, or Cephas (Peter) is irrelevant. Indeed, all are to be followers of the Messiah, Jesus.

1 Corinthians 3:10-15, The importance of a good foundation
By the grace God has given me, I laid a foundation as an expert builder, and someone else is building on it. But each one should be careful how he builds. For no one can lay any foundation other than the one already laid, which is Jesus Christ.

If any man builds on this foundation using gold, silver, costly stones, wood, hay or straw, his work will be shown for what it is, because the Day will bring it to light. It will be revealed with fire, and the fire will test the quality of each man's work. If what he has built survives, he will receive his reward.

If it is burned up, he will suffer loss; he himself will be saved, but only as one escaping through the flames.

The foundation is important. Outward appearances are irrelevant.  The concept of fire fits Paul's building metaphor: a good building survives a fire, a poor one does not.  Fire burns away the outside painting and reveals the true inside structure.

1 Corinthians 3:16-23, We are God's temple
Don't you know that you yourselves are God's temple and that God's Spirit lives in you? If anyone destroys God's temple, God will destroy him; for God's temple is sacred, and you are that temple.

Do not deceive yourselves. If any one of you thinks he is wise by the standards of this age, he should become a "fool" so that he may become wise. For the wisdom of this world is foolishness in God's sight. As it is written: "He catches the wise in their craftiness";  and again, "The Lord knows that the thoughts of the wise are futile."

So then, no more boasting about men! All things are yours, whether Paul or Apollos or Cephas or the world or life or death or the present or the future--all are yours, and you are of Christ, and Christ is of God.

The divisions in the church in Corinth are echoed in the Christian church today, with various denominations claiming some type of special insight into the kingdom.  Yet we are all, together, to follow Christ.

The Old Testament quote in verse 19 is from Job 5:13.  The quote in verse 20 is from Psalm 94:11.

I Corinthians 2, Wisdom of the Spirit

Paul began his letter to Corinth by reminding his readers of the life available in the Holy Spirit and confronting them for divisions based on various leadership choices.  He continues to discuss these issues, focusing on spiritual wisdom.

1 Corinthians 2: 1-5, Weakness in Jesus
When I came to you, brothers, I did not come with eloquence or superior wisdom as I proclaimed to you the testimony about God. For I resolved to know nothing while I was with you except Jesus Christ and him crucified.

I came to you in weakness and fear, and with much trembling. My message and my preaching were not with wise and persuasive words, but with a demonstration of the Spirit's power, so that your faith might not rest on men's wisdom, but on God's power.

Jesus is the priority; it is to his kingdom, his country, to which we belong.  This membership, and the accompanying wisdom, is much simpler (and yet much deeper) than any temporary eloquence of speech or philosophy.

1 Corinthians 2:6-10a, A different wisdom

We do, however, speak a message of wisdom among the mature, but not the wisdom of this age or of the rulers of this age, who are coming to nothing. No, we speak of God's secret wisdom, a wisdom that has been hidden and that God destined for our glory before time began.

None of the rulers of this age understood it, for if they had, they would not have crucified the Lord of glory. However, as it is written: "No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him" -- but God has revealed it to us by his Spirit.

The shortterm "wisdom" of the world is very different from the longterm eternal wisdom offered by the crucified and resurrected Messiah.

The Old Testament quote in verse 9 is from Isaiah 64:4.

1 Corinthians 2: 10b-13, The Holy Spirit reveals God's thoughts
The Spirit searches all things, even the deep things of God. For who among men knows the thoughts of a man except the man's spirit within him? In the same way no one knows the thoughts of God except the Spirit of God.

We have not received the spirit of the world but the Spirit who is from God, that we may understand what God has freely given us. This is what we speak, not in words taught us by human wisdom but in words taught by the Spirit, expressing spiritual truths in spiritual words.

Paul emphasizes the work of the Holy Spirit, acting internally, aiding the believer to begin to see things from God's perspective.  This follows an argument similar to that expressed in Romans 8 (which was written from Corinth.)

1 Corinthians 2: 14-16, Have the "mind of Christ"
The man without the Spirit does not accept the things that come from the Spirit of God, for they are foolishness to him, and he cannot understand them, because they are spiritually discerned. The spiritual man makes judgments about all things, but he himself is not subject to any man's judgment: "For who has known the mind of the Lord that he may instruct him?" But we have the mind of Christ.

This is a significant theme of Paul's: if one is constantly immersed in the temporary social and intellectual realm of "earth" then one has a mindset very different from that given by the Holy Spirit, given to those who are part of the kingdom of heaven.  (In this way -- as to be elaborated later -- the followers of the Messiah are to be "ambassadors", remembering our "true country" while living in this one.)

The Old Testament quote in verse 16 is from Isaiah 40:13. Even when speaking to Gentiles, Paul repeatedly relies on the Jewish ("Old Testament") scriptures.

I Corinthian 1, A Higher Calling

After reading the book of Acts, we have looked at some early letters by the apostle Paul -- his letters to the Galatians and the Thessalonians.  We will now look at his letters to Corinth, before returning to read through one of the gospels.

The church begun in Corinth was in the midst of a pagan and chaotic society.  Paul wrote several letters to the church dealing with practical concerns and questions that they had posed to him. Over the next three weeks we look at the "First Letter" to the church in Corinth.

1 Corinthians 1:1-3, Greeting
Paul, called to be an apostle of Christ Jesus by the will of God, and our brother Sosthenes, to the church of God in Corinth, to those sanctified in Christ Jesus and called to be holy, together with all those everywhere who call on the name of our Lord Jesus Christ--their Lord and ours:

Grace and peace to you from God our Father and the Lord Jesus Christ.

In this fairly traditional greeting, Paul lays out the writers (he and Sothenes) and addresses the people of the Corinth church, reminding them of their high calling.

1 Corinthians 1:4-9, General calling

I always thank God for you because of his grace given you in Christ Jesus. For in him you have been enriched in every way--in all your speaking and in all your knowledge--because our testimony about Christ was confirmed in you. Therefore you do not lack any spiritual gift as you eagerly wait for our Lord Jesus Christ to be revealed. He will keep you strong to the end, so that you will be blameless on the day of our Lord Jesus Christ. God, who has called you into fellowship with his Son Jesus Christ our Lord, is faithful.

Paul elaborates on this calling. The people of the church have been provided everything they need through Christ and the Holy Spirit.

1 Corinthians 1:10-13, Concerns about divisions

I appeal to you, brothers, in the name of our Lord Jesus Christ, that all of you agree with one another so that there may be no divisions among you and that you may be perfectly united in mind and thought.

My brothers, some from Chloe's household have informed me that there are quarrels among you. What I mean is this: One of you says, "I follow Paul"; another, "I follow Apollos"; another, "I follow Cephas"; still another, "I follow Christ."

Is Christ divided? Was Paul crucified for you? Were you baptized into the name of Paul?

One sign of the love of God is a unity and common encouragement among the followers of God. Paul is distressed that in Corinth the Christians are breaking into factions, depending upon which teacher they claim as theirs.  

Sadly, this has only gotten worse over the millenia since.

1 Corinthians 1:14-17, Division caused by baptism

I am thankful that I did not baptize any of you except Crispus and Gaius, so no one can say that you were baptized into my name. (Yes, I also baptized the household of Stephanas; beyond that, I don't remember if I baptized anyone else.) For Christ did not send me to baptize, but to preach the gospel--not with words of human wisdom, lest the cross of Christ be emptied of its power.

One of the conflicts in Corinth is over baptism.  Here the conflict is related to the identification with a certain teacher, not the mode of baptism. But note how uninterested Paul is in baptism as he says, "I didn't baptize anyone... well except Crispus and Gaius.  Oops, right, I also baptized the household of Stephanas...."  Paul would be shocked that modern churches have moved the dispute to the "mode" of baptism.  None of these disagreements should allow conflict among the people of God's kingdom!

1 Corinthians 1:18-25, The "Weakness" of the Gospel
For the message of the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God. For it is written: "I will destroy the wisdom of the wise; the intelligence of the intelligent I will frustrate."

Where is the wise man? Where is the scholar? Where is the philosopher of this age? Has not God made foolish the wisdom of the world? For since in the wisdom of God the world through its wisdom did not know him, God was pleased through the foolishness of what was preached to save those who believe.

Jews demand miraculous signs and Greeks look for wisdom, but we preach Christ crucified: a stumbling block to Jews and foolishness to Gentiles, but to those whom God has called, both Jews and Greeks, Christ the power of God and the wisdom of God. For the foolishness of God is wiser than man's wisdom, and the weakness of God is stronger than man's strength.

The Old Testament quote in verse 19 is from Isaiah 29:14.

The earthly, naturalistic view of things -- in which the current "wisdom" fad is all that matters -- is shortsighted. Yes, it may bring a certain social standing, as all fads do. Paul is not going to give himself over to the human hierarchy of scholarship.  Elsewhere, Paul will make careful intellectual arguments about the case for Christ (see Acts 17: 16-34 in Athens, and the arguments in the letter to the Romans) but he is not subservient to intellectual "wisdom".

1 Corinthians 1 26-31, God's standards are utterly different
Brothers, think of what you were when you were called. Not many of you were wise by human standards; not many were influential; not many were of noble birth. But God chose the foolish things of the world to shame the wise; God chose the weak things of the world to shame the strong. He chose the lowly things of this world and the despised things--and the things that are not--to nullify the things that are, so that no one may boast before him.

It is because of him that you are in Christ Jesus, who has become for us wisdom from God--that is, our righteousness, holiness and redemption. Therefore, as it is written: "Let him who boasts boast in the Lord."

The Old Testament quote in verse 31 is from Jeremiah 9:24.

Why has God chosen this path?  Why does he work with the weak, poor, humble?  I'm not sure we are eager for the answer....  But it has been God's plan through ancient Israel, from his choice of Abraham, Judah, Joseph, Moses, Rahab, Gideon, David.  Jesus repeated this message throughout his ministry.  Paul will elaborate on Jesus and this ministry of the "weak" or "foolish" in the next chapter.

Acts 19, Paul in Ephesus

Leaving Antioch on his third missionary journey, Paul returns to modern Turkey, to towns he has previous visited. One of them is the relatively large city of Ephesus.

Acts 19:1-7, Baptizing followers in Ephesus
While Apollos was at Corinth, Paul took the road through the interior and arrived at Ephesus. There he found some disciples and asked them, "Did you receive the Holy Spirit when You believed?" They answered, "No, we have not even heard that there is a Holy Spirit."

So Paul asked, "Then what baptism did you receive?" 

"John's baptism," they replied.

Paul said, "John's baptism was a baptism of repentance. He told the people to believe in the one coming after him, that is, in Jesus."

On hearing this, they were baptized into the name of the Lord Jesus.  When Paul placed his hands on them, the Holy Spirit came on them, and they spoke in tongues and prophesied. There were about twelve men in all.

Paul arrives at Ephesus to learn of disciples of Jesus who know of John's baptism, but do not know of Pentecost.  These disciples (coincidentally about 12) may not even know of the crucifixion and resurrection (and its meaning) and so are not yet fully aware of Who Jesus is.

Acts 19:8-12, Synagogue in Ephesus
Paul entered the synagogue and spoke boldly there for three months, arguing persuasively about the kingdom of God. But some of them became obstinate; they refused to believe and publicly maligned the Way. So Paul left them. He took the disciples with him and had discussions daily in the lecture hall of Tyrannus.

This went on for two years, so that all the Jews and Greeks who lived in the province of Asia heard the word of the Lord. God did extraordinary miracles through Paul, so that even handkerchiefs and aprons that had touched him were taken to the sick, and their illnesses were cured and the evil spirits left them.

Paul stays in Ephesus for two years, so it plays a central role in his ministry. Ephesus was a large port city in that day, on the Kaystros River, but it would be destroyed by an earthquake in the seventh century and now its ruins are a tourist designation, five miles from the ocean, as the Kaystros has filled with silt.  I spent an afternoon there in summer 2012, a tourist among the ruins.

Acts 19:13-17, Seven sons of Sceva
Some Jews who went around driving out evil spirits tried to invoke the name of the Lord Jesus over those who were demon-possessed. They would say, "In the name of Jesus, whom Paul preaches, I command you to come out." Seven sons of Sceva, a Jewish chief priest, were doing this. [One day] the evil spirit answered them, "Jesus I know, and I know about Paul, but who are you?" Then the man who had the evil spirit jumped on them and overpowered them all. He gave them such a beating that they ran out of the house naked and bleeding.

When this became known to the Jews and Greeks living in Ephesus, they were all seized with fear, and the name of the Lord Jesus was held in high honor.

Luke records a strange event in which even the evil spirits acknowledge Paul ... but aren't willing to abide by fake exorcists!

Acts 19:18-22, Giving up their books and beliefs
Many of those who believed now came and openly confessed their evil deeds. A number who had practiced sorcery brought their scrolls together and burned them publicly. When they calculated the value of the scrolls, the total came to fifty thousand drachmas. In this way the word of the Lord spread widely and grew in  power.

After all this had happened, Paul decided to go to Jerusalem, passing through Macedonia and Achaia. "After I have been there," he said, "I must visit Rome also." He sent two of his helpers, Timothy and Erastus, to Macedonia, while he stayed in the province of Asia a little longer.

The NIV footnotes say that a drachma (verse 19) was a silver coin worth about a day's wages.  The gospel has made a serious dent in the finances of the worshipers of Artemis!  (Then, as today, people react strongly to beliefs that hurt their pocketbooks!)

Acts 19:23-27, Demetrius and the sellers of Artemis

About that time there arose a great disturbance about the Way. A silversmith named Demetrius, who made silver shrines of Artemis, brought in no little business for the craftsmen. He called them together, along with the workmen in related  trades, and said: "Men, you know we receive a good income from this business. And you see and hear how this fellow Paul has convinced and led astray large numbers of people here in Ephesus and in practically the whole province of Asia. He says that  man-made gods are no gods at all. There is danger not only that our trade will lose its good name, but also that the temple of the great goddess Artemis will be discredited, and the goddess herself, who is worshiped throughout the province of Asia and the world, will be robbed of her divine majesty."

Poor Artemis, unable to defend herself!  (One should always be suspicious of any deities -- Artemis, Allah, Jesus -- that rely on their followers to protect them!)

Acts 19:28-34, "Great is Artemis"
When they heard this, they were furious and began shouting: "Great is Artemis of the Ephesians!" Soon the whole city was in an uproar. The people seized Gaius and Aristarchus, Paul's traveling companions from Macedonia, and rushed as one man into the theater.

Paul wanted to appear before the crowd, but the disciples would not let him. Even some of the officials of the province, friends of Paul, sent him a message begging him not to venture into the theater. The assembly was in confusion: Some were shouting one thing, some another. Most of the people did not even know why they were there. The Jews pushed Alexander to the front, and some of the crowd shouted instructions to him. He motioned for silence in order to make a defense before the people. But when they realized he was a Jew, they all shouted in  unison for about two hours: "Great is Artemis of the Ephesians!"

It is good that the "disciples" don't let Paul address the crowd!

Acts 19:35-41, City clerk: "The courts are open...."
The city clerk quieted the crowd and said: "Men of Ephesus, doesn't all the world know that the city of Ephesus is the guardian of the temple of the great Artemis and of her image, which fell from heaven? Therefore, since these facts are undeniable, you ought to be quiet and not do anything rash. You have brought these men here, though they have neither robbed temples nor blasphemed our goddess.

If, then, Demetrius and his fellow craftsmen have a grievance against anybody, the courts are open and there are proconsuls. They can press charges. If there is anything further you want to bring up, it must be settled in a legal assembly. As it is, we are in danger of being charged with rioting because of today's events. In that case we would not be able to account for this commotion, since there is no reason for it."

After he had said this, he dismissed the assembly.

Luke's impression of the city clerk here is considerably better than his account of Gallio of Corinth, of the previous chapter.

It is likely that Paul wrote his first letter to the Corinthians during his three years in Ephesus.

Acts 18, Paul in Corinth; Third Journey Begins

Paul has spent time in Athens, talking to the Greeks, and now moves further west to another Greek city, a center of commerce and Greek culture.

Acts 18:1-8, Paul in Corinth
After this, Paul left Athens and went to Corinth. There he met a Jew named Aquila, a native of Pontus, who had recently come from Italy with his wife Priscilla, because Claudius had ordered all the Jews to leave Rome. Paul went to see them, and because he was a tentmaker as they were, he stayed and worked with them.

Every Sabbath he reasoned in the synagogue, trying to persuade Jews and Greeks. When Silas and Timothy came from Macedonia, Paul devoted himself exclusively to preaching, testifying to the Jews that Jesus was the Christ. But when the Jews opposed Paul and became abusive, he shook out his clothes in protest and said to them, "Your blood be on your own heads! I am clear of my responsibility. From now on I will go to the Gentiles."

Then Paul left the synagogue and went next door to the house of Titius Justus, a worshiper of God. Crispus, the synagogue ruler, and his entire household believed in the Lord; and many of the Corinthians who heard him believed and were baptized.

A turning point occurs. Paul begins to understand that the Gentiles are more receptive to the gospel and decides to go to them first.  Still, he continues to care about his Jewish brothers and sisters and we will see Paul speaking to Jews in the synagogues in later chapters. 

Luke notes that the local synagogue ruler becomes a believer.

Acts 18:9-11, Stay  in Corinth!
One night the Lord spoke to Paul in a vision: "Do not be afraid; keep on speaking, do not be silent.  For I am with you, and no one is going to attack and harm you, because I have many people in this city."  So Paul stayed for a year and a half, teaching them the word  of God.

With encouragement from the divine vision, Paul devotes portions of two years to building the church in Corinth.  He will later send them letters, working through a number of practical and theological problems.

Acts 18:12-17, Attack before Gallio
While Gallio was proconsul of Achaia, the Jews made a united attack on Paul and brought him into court. "This man," they charged, "is persuading the people to worship God in ways contrary to the law."

Just as Paul was about to speak, Gallio said to the Jews, "If you Jews were making a complaint about some misdemeanor or serious crime, it would be reasonable for me to listen to you. But since it involves questions about words and names and your own law--settle the matter yourselves. I will not be a judge of such things."  So he had them ejected from the court.

Then they all turned on Sosthenes the synagogue ruler and beat him in front of the court. But Gallio showed no concern whatever.

Luke expresses surprise at the apathy of Gallio.  

Acts 18:18-22, Journey to Ephesus
Paul stayed on in Corinth for some time. Then he left the brothers and sailed for Syria, accompanied by Priscilla and Aquila. Before he sailed, he had his hair cut off at Cenchrea because of a vow he had taken. They arrived at Ephesus, where Paul left Priscilla and Aquila. He himself went into the synagogue and reasoned with the Jews.

When they asked him to spend more time with them, he declined. But as he left, he promised, "I will come back if it is God's will." Then he set sail from Ephesus. When he landed at Caesarea, he went up and greeted the church and then went down to Antioch.

Paul returns home to the church in Antioch.  The trip is covered quickly in Luke's telling, other than the vow made in Cenchrea (a port of Corinth.)  At Cenchrea Paul apparently gets on a ship and crosses the Aegean to Ephesus, a port city on the opposite side.  Ephesus is a major city in this time and Paul had set up a significant ministry there.  Later he will write them a letter which comes into our canon as the Epistle to the Ephesians.

It is not clear what vow Paul is taking in Cenchrea. It may be one begun there, intended to end in Jerusalem in Acts 21:20-26. If so, Paul may be taking a Nazarite vow -- see this Stackexchange page.

Acts 18:23-28, A new trip! And growth in Ephesus!

After spending some time in Antioch, Paul set out from there and traveled from place to place throughout the region of Galatia and Phrygia, strengthening all the disciples. Meanwhile a Jew named Apollos, a native of Alexandria, came to Ephesus. He was a learned man, with a thorough knowledge of the Scriptures. He had been instructed in the way of the Lord, and he spoke with great fervor and taught about Jesus accurately, though he knew only the baptism of John.

He began to speak boldly in the synagogue. When Priscilla and Aquila heard him, they invited him to their home and explained to him the way of God more adequately. When Apollos wanted to go to Achaia, the brothers encouraged him and wrote to the disciples there to welcome him. On arriving, he was a great help to those who by grace had believed. For he vigorously refuted the Jews in public debate, proving from the Scriptures that Jesus was the Christ.

The third missionary journey begins, with a return through Asia Minor, visiting the churches (synagogues) developed in the previous journeys.  

Meanwhile, Luke digresses to tell us of Apollos in Ephesus.  Apparently Apollos knows of Jesus, but not of Pentecost.  The knowledge Apollos has might be equated with that one has after reading the gospel of Mark or Matthew.  Luke emphasizes that because Apollos knew the Scriptures (that is, what Christians today would call the Old Testament) and because Apollos knew about Jesus, he was able to accurately link the Jewish Scriptures to the Messiah.  (I would love to know what Apollos taught! Could it be summarized in the book of Hebrews?)