Act 15:23-24 They wrote this letter by them: The apostles, the elders, and the brethren, To the brethren who are of the Gentiles in Antioch, Syria, and Cilicia: Greetings. Since we have heard that some who went out from us have troubled you with words, unsettling your souls, saying, "You must be circumcised and keep the law" —to whom we gave no such commandment—"
The Holy Spirit guided the Council in Jerusalem to establish the most important doctrine concerning the Old Covenant, which was prophesied to be replaced by the New Covenant of grace. So Gentile converts (Christians) must not be partakers of any of the law including feasts, sacrifices, worships, traditions, offerings etc.
Paul was one of those sent to inform the churches to distance themselves from the law of the Old Covenant. In Antioch, they stayed on to encourage and teach both Jewish and Gentile converts the doctrines of the Apostles
Acts 15:25-30 it seemed good to us, being assembled with one accord, to send chosen men to you with our beloved Barnabas and Paul, men who have risked their lives for the name of our Lord Jesus Christ. We have therefore sent Judas and Silas, who will also report the same things by word of mouth. For it seemed good to the Holy Spirit, and to us, to lay upon you no greater burden than these necessary things: that you abstain from things offered to idols, from blood, from things strangled, and from sexual immorality. If you keep yourselves from these, you will do well. So when they were sent off, they came to Antioch; and when they had gathered the multitude together, they delivered the letter.
Paul disputed with Barnabas
Act 15:36-37 Then after some days Paul said to Barnabas, "Let us now go back and visit our brethren in every city where we have preached the word of the Lord, and see how they are doing." Now Barnabas was determined to take with them John called Mark.
After a while, Paul decided to visit the new churches to encourage the new brethren there. The dispute of Mark led Paul and Barnabas to split.
Acts 15:38-40 But Paul insisted that they should not take with them the one who had departed from them in Pamphylia, and had not gone with them to the work. Then the contention became so sharp that they parted from one another. And so Barnabas took Mark and sailed to Cyprus; but Paul chose Silas and departed, being commended by the brethren to the grace of God.
Hypocrisy of Paul
Acts 16:1, 3-4 Then he came to Derbe and Lystra. And behold, a certain disciple was there, named Timothy, the son of a certain Jewish woman who believed, but his father was Greek... Paul wanted to have him go on with him. And he took him and circumcised him because of the Jews who were in that region, for they all knew that his father was Greek. And as they went through the cities, they delivered to them the decrees to keep, which were determined by the apostles and elders at Jerusalem.
They were sent to inform churches that Gentiles need not observe the law after their conversion, yet Paul took Timothy to get him circumcised - this is hypocrisy and rebellion.
This clearly showed that Paul was still unaware that the gospel of grace was for both Jews and Gentiles alike. The Jewish converts were still stuck to the law and Jewish traditions, for they still kept themselves away from other Christians.
Phi 3:12 Not that I have already attained, or am already perfected; but I press on, that I may lay hold of that for which Christ Jesus has also laid hold of me.