Acts 19:20 marks the the apex of the move of God's Word in the first century.  Under the ministry of the Apostle Paul the word moved dynamically in Asia and prevailed.  It was at this great prevailing point that the Apostle Paul made a decision, contrary to the will of God, that ultimately resulted in the following declaration to Timothy a few years later:

II Timothy 1:15
   This thou knowest, that all they which are in Asia be turned away from me;

Certainly it was not God's Will for the movement of His Word to slow down or terminate with the prevailing word in Asia.  God wanted Paul to continue moving His Word to Rome and beyond.  But Paul made a decision to visit Jerusalem instead of going on to Rome.  This decision, we will see, was contrary to God's Will and resulted in Paul's imprisonment for most of the rest of his life.  Why did he go to Jerusalem when God had told him not to go?  What was so important that it was worth risking the move of God's Word?

To answer these questions we must look at what Paul was teaching and what was happening in the church in Jerusalem.  We will start a few years before the word prevailed in Asia when Paul had just begun moving the truth of God's Word among the Gentile cities.

Acts 15:1-2
   And certain men which came down from Judaea [Jerusalem] taught the brethren, and said, Except ye be circumcised after the manner of Moses, ye cannot be saved.
   When therefore Paul and Barnabas had no small dissension and disputation with them, they determined that Paul and Barnabas, and certain other of them, should go up to Jerusalem unto the apostles and elders about this question.

[Jerusalem was built on hills and was the location of the temple of God.  Therefore whenever people came from Jerusalem the word of God says they "came down from Jerusalem" and whenever people went to Jerusalem the word of God says they "went up to Jerusalem."  Has nothing to do with north and south.]

At this meeting of the Apostles and elders, believers who had formal training and background in the law of Moses put forth their opinion that the Gentile believers needed to keep the law to be saved.

Acts 15:5
   But there rose up certain of the sect of the Pharisees which believed, saying, That it was needful to circumcise them, and to command them to keep the law of Moses.

The Apostle Peter answered this opinion with the Word of God and said,

Acts 15:11
   But we believe that through the grace of the Lord Jesus Christ we shall be saved, even as they.

The resulting pronouncement of James and the rest of this council was that the believers who had told the Gentiles they had to keep the law were not speaking for the Apostles and elders; nor were they holding forth the truth of the Word.

Acts 15:24
   Forasmuch as we have heard, that certain which went out from us have troubled you with words, subverting your souls, saying, Ye must be circumcised, and keep the law: to whom we gave no such commandment:

Following this council in Acts 15 the Apostle Paul continued to move the doctrine of the grace of God among the Gentiles until, as we read in Acts 19, the Word of God grew and prevailed.  Meanwhile the elders in Jerusalem continued to adhere to the law of Moses and this erroneous doctrine began to prevail among those who stayed in Jerusalem where the movement of God's Word had started.  While the believers in Jerusalem continued to keep the law of Moses, the Apostle Paul taught:

Romans 3:20a
   Therefore by the deeds of the law there shall no flesh be justified in his sight:
Romans 3:21a
   But now the righteousness of God without the law is manifested,
Romans 3:28
   Therefore we conclude that a man is justified by faith without the deeds of the law.
Romans 6:14
   For sin shall not have dominion over you: for ye are not under the law, but under grace.
Romans 7:4
   Wherefore, my brethren, ye also are become dead to the law by the body of Christ;
Romans 10:4
   For Christ is the end of the law for righteousness to every one that believeth.
Galatians 2:16
   Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.
Galatians 5:18
   But if ye be led of the Spirit, ye are not under the law.
Ephesians 2:15a
   Having abolished in his flesh the enmity, even the law of commandments contained in ordinances;
Philippians 3:9
   And be found in him, not having mine own righteousness, which is of the law, but that which is through the faith of Christ, the righteousness which is of God by faith:

Acts 19:20-21
   So mightily grew the word of God and prevailed.
   After these things were ended, Paul purposed in the spirit, when he had passed through  Macedonia and Achaia, to go to Jerusalem, saying, After I have been there, I must also see Rome.

The word "spirit" in verse 21 is the word for "mind" in the Aramaic text.  This was not a spiritually right decision as we will see as we examine the rest of the context.  God did not want Paul to go.  Paul purposed to go in his own mind.  However, he added "after I have been there, I must also see Rome."

I believe Paul knew that God wanted him to move on to Rome.  But Paul decided to travel to Jerusalem instead of continuing with the prevailing move of God's Word.  This decision must have been troubling to him, as he decided to walk alone to Assos while the believers traveling with him went by ship.  I am sure as he walked he talked this decision over with his Heavenly Father.

Acts 20:13
   And we went before to ship, and sailed unto Assos, there intending to take in Paul: for so had he appointed, minding himself to go afoot.

However, God did not persuade him.   Paul made up his mind to go to Jerusalem.  Perhaps it was during his walk that he decided (wrongly) that he would have a better chance of convincing the law bound believers in Jerusalem if he visited them on the birthday of the church (Pentecost.)  Before God has others tell you of your error, He will always tell you first. As Paul walked and talked with God on his way to Assos, Paul set his mind on Jerusalem and getting there by Pentecost.  At the same time God set His mind on warning Paul and trying to get him to stop.  God is a God of free will.  He will do everything to try and keep us walking on His Word.  But if we stubbornly persist in walking contrary to the Word, God cannot and will not overstep free will.

In his rush to reach Jerusalem by Pentecost, Paul sailed by Ephesus which was the hub for the movement of the Word in Asia Minor and landed at Miletus.

Acts 20:16
   For Paul had determined to sail by Ephesus, because he would not spend time in Asia: for he hasted, if it were possible for him, to be at Jerusalem the day of Pentecost.

 At Miletus, he sent for the elders from Ephesus and spoke to the leadership he had trained in God's Word.

Acts 20:22-25
   And now, behold I go bound in the spirit unto Jerusalem, not knowing the things that shall befall me there:
   Save that the Holy Ghost witnesseth in every city, saying that bonds and afflictions abide me.
   But none of these things move me, neither count I my life dear unto myself, so that I might finish my course with joy, and the ministry, which I have received of the Lord Jesus, to testify the gospel of the grace of God.
   And now, behold, I know that ye all, among whom I have gone preaching the kingdom of God, shall see my face no more.

Paul saw this visit to Jerusalem as part of his ministry "to testify of the grace of God."  I really think he thought he could persuade the believers in Jerusalem.  But he was bound in the spirit.  Spiritually, God was trying to hold him back.

In every city he visited, God sent some believer to tell Paul not to go; and that bonds and afflictions were waiting for him if he went.  God did not want him to go!  I do not know what Paul thought was going to happen to him in Jerusalem, but he told the believers here in Miletus that they would not see him again.  He called this visit "a finish to his course."  Clearly, he knew he was not suppose to go.  But he kept going anyway.

Paul kept moving toward Jerusalem and when his ship landed in Tyre they met some more believers.

Acts 21:4
   And finding disciples, we tarried there seven days: who said to Paul through the Spirit, that he should not go up to Jerusalem.

The Will of God is clear as crystal.  DON'T GO PAUL!  It was important to God.  It was important to the move of the Word of God.  Yet Paul had decided and he was not listening to anyone but his own mind.  He was going.  Paul moved on to Caesarea and stayed with Philip the evangelist.

Acts 21:9
   And the same man had four daughters, virgins, which did prophesy.

The Word of God does not tell us what Philip's daughters prophesied about.  But in every city believers had been telling Paul not to go to Jerusalem.  In the context, the prophesy must have contained the same message.  As they were staying with Philip they also received a visitor from Jerusalem:

Acts 21:10-11
   And as we tarried there many days, there came down from Judaea [Jerusalem] a certain prophet named Agabus.
   And when he was come unto us, he took Paul's girdle, and bound his own hands and feet, and said, Thus saith the Holy Ghost [GOD!], So shall the Jews at Jerusalem bind the man that owneth this girdle, and shall deliver him into the hands of the Gentiles.

Agabus was a well known prophet.  The believers knew that his prophesies had come to pass in the past.  They trusted that he was speaking God's Word.  When the believers with Paul heard his description of what awaited Paul in Jerusalem, they tried one last time to persuade Paul not to go.

Acts 21:12
   And when we heard these things, both we, and they of that place, besought him not to go up to Jerusalem.

Once again, Paul responded with his resolve to go even at the risk of his own life.  He sincerely believed he could make a difference in Jerusalem.  But he was wrong.  He was clearly outside of the Will of God.

Acts 21:13
   Then Paul answered, What mean ye to weep and to break mine heart?  for I am ready not to be bound only, but also to die at Jerusalem for the name of the Lord Jesus.

Religious? Yes. Sincere? Yes. Committed? Yes.  Persuaded?  Yes. But was he right? NO NO NO.  The Will of God was clearly DO NOT GO.

Acts 21:14
   And when he would not be persuaded, we ceased, saying, The will of the Lord be done.

The original text did not have commas.  The commas in this verse change the meaning.  When the believers could not persuade Paul, they stopped saying "do the will of God" for clearly Paul had decided he was not going to obey the revelation to not go to Jerusalem.

So what did Paul find when he got to Jerusalem in the next verse.  He found a warm welcome from the believers followed immediately by a plea to commit to the law of Moses.  He found the elders acting in fear of the multitude of Judean believers.  He found the church committed to the law and far more willing to deliver him to prison than to listen to the truth of God's Word.  He found he made a mistake!

Acts 21:19-20
   And when he had saluted them, he declared particularly what things God had wrought among the Gentiles by his ministry.
   And when they heard it, they glorified the Lord, and said unto him, Thou seest, brother, how many thousands of Jews there are which believe; and they are all zealous of the law:
   And they are informed of thee, that thou teachest all the Jews which are among the Gentiles to forsake Moses, saying that they ought not to circumcise their children, neither to walk after the customs.

The believers in Jerusalem set Paul up, got him arrested, and then he spent most of the rest of his life in prison.  Why did he go?  I guess he really believed he could correct the doctrinal error in the church in Jerusalem.

Did God give up on Paul because he disobeyed?  No! God stood with him even in prison and simply restated the original revelation to move His Word in Rome.

Acts 23:11
   And the night following the Lord stood by him [in prison], and said, Be of good cheer, Paul: for as thou hast testified of me in Jerusalem, so must thou bear witness also at Rome.

God stood with him throughout his years in prison and gave him an even greater knowledge of the grace of God.  The greatest revelations ever given to the Christian church were revealed to the Apostle Paul during these years.  Yet the move of the word quickly died.

Although we have greater knowledge of the grace of God today thanks to the revelation Paul received, the word never again prevailed in the lives of the first century Christians.  The lessons to be learned from Paul's disobedience are to move ahead;  speak God's Word; live God's Word; and, most of all, obey God.