I listened to that sermon and it did not sit right with me.
If Paul was wrong in going to Jerusalem, there is about 1/3rd of Acts that would drop into a parenthesis, because it establishes truth on wrong premises.
First Paul determined in the Spirit:
Acts 19:21After 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.
Secondly he was bound in the Spirit
Acts 20:22 And now, behold, I go bound in the spirit unto Jerusalem, not knowing the things that shall befall me there:
If Paul was disobedient, he would not be bound in Spirit, but in his soul. The Greek word used in both cases is πνεύμα (Spirit), not ψυχή (soul)
in Acts 23:11 Paul got a confirmation that his decision to go to Jerusalem was in fact right:
Acts 23:11 And the night following the Lord stood by him, and said, Be of good cheer, Paul: for as thou hast testified of me in Jerusalem, so must thou bear witness also at Rome.
Furthermore, Paul understood, that, although he was sent to the Gentiles, the Gospel must be preached to the Jew first.
Paul received a prophetic word that he would testify before rulers and kings. Had he not gone to Jerusalem, he would unlikely have testified before King Agrippa, and he would not have been sent in chains to appear before Cesar.
Others prophesied to Paul, that imprisonment would expect him in Jerusalem, but ADDED on through their own interpretation that he should not go. It was again Agabus, who set it straigt, by saying the same thing without the soul-inspired addition that he sould not go.
Read what the bibles says in Acts 21
10 And as we tarried there many days, there came down from Judaea a certain prophet, named Agabus.
11 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, So shall the Jews at Jerusalem bind the man that owneth this girdle, and shall deliver him into the hands of the Gentiles.
12 And when we heard these things, both we, and they of that place, besought him not to go up to Jerusalem.
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.
14 And when he would not be persuaded, we ceased, saying, THE WILL OF THE LORD BE DONE.
God's purpose was for Paul to testify before the rules in the capital of the religous world, Jerusalem, the capital of the intellectual world, which was Athens, and the captial of the political and military power, which was Rome.
Paul was not on a detour like Jonah or Barnabas or Demas. He was in the will of God.
In fact, Paul wanted to show that he was willing to be cut off from Got if it would help to save some of his people, just like Christ and Moses. Paul set an example for generations of persecuted Christians not to shun imprisonment, torture and death. Paul was as effective, perhaps even more effective a missionary in chains than as a free man.
Had Paul not gone to Jerusalem, the Jews could accuse him of cowardice, but he stuffed their mouths by showing them that he wanted their salvation more than his own life.
So he heaped firery coals of conviction on every Jew who accused Paul of treason.
If you take Warren Wiersbe's statements further you would throw a lot of doubt on a big part of the New Testament.
I agree with what Wiersbe says in conclusion about detours in general, though not in this particular case.
The only thing that baffles me, is that upon the advice of Christ believing Jewish leaders he partook in a cleansing ritual and shared the cost for an offering of men who took a vow - but this, I guess, is another topic..