Here's one of the main reasons there were some Jews who tried to kill Paul. They persecuted him wherever he went. He was speaking against circumcision. It was no longer needed because of the cross.
Now, brothers, if I am still preaching circumcision, why am I still being persecuted? In that case the offense of the cross has been abolished. Galatians 1:11<
Here he is breaking the tradition of Jewish people for thousands of years. He explains why.
Therefore let it be known to you, brothers, that through Jesus the forgiveness of sins is proclaimed to you. 39Through Him everyone who believes is justified from everything you could not be justified from by the law of Moses. Acts 13:38-39<
Being filled with jealousy seems to be the instigator of all the hatred towards Paul...
A lot of the Jews were also filled with jealousy because a lot of people are listening to him instead of to them their religious leaders.
Act 13:45 But when the Jews saw the multitudes, they were filled with envy, and spake against those things which were spoken by Paul, contradicting and blaspheming.<
These religious leaders are again stating that the new converts needed to be circumcised and follow the law of Moses. They are contradicting everything Paul just told them.
Act 15:1 And certain men which came down from Judaea taught the brethren, and said, Except ye be circumcised after the manner of Moses, ye cannot be saved.<
He was upsetting whole tradition of the Jewish culture, Saying you don't need to be circumcised or follow the law anymore. He was showing them a new way that a man is justified by the faith of Jesus Christ.<
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 2:16<
He is continuing to teach a new way of salvation apart from the law. And there is no difference now between Jew or Gentile.
And now apart from law hath the righteousness of God been manifested, testified to by the law and the prophets, 22and the righteousness of God [is] through the faith of Jesus Christ to all, and upon all those believing, — for there is no difference, <
Jews and Gentiles are now on the same footing and that does not go over well with religious Jews.
These are a few examples of why the Jews hated Paul And wanted to kill him.
The Greeks as well wanted to kill Paul for disrupting their livelihood of making idols that were used to worship the pagan gods. Money was being lost because of the power of God setting people free through Paul's ministry of Jesus Christ.
They was also an incident where he delivered a spirit from a girl who was possessed and made her masters much money. When she was set free the masters or extremely upset because she no longer could make money for them. Again he was disrupting customs to the worship of pagan gods.
Eventually Paul grew so aggravated that he turned and said to the spirit, “In the name of Jesus Christ I command you to come out of her!” And the spirit left her at that very moment.
When the girl’s owners saw that their hope of making money was gone, they seized Paul and Silas and dragged them before the authorities in the marketplace. Acts16:19<
Jews hated him for changing their customs as well as the Greeks hated him for changing their customs. God was doing a new work on the earth.
Watch out, then, that what was spoken by the prophets does not happen to you:
Look, you scoffers,
wonder and perish!
For I am doing a work in your days
that you would never believe,
even if someone told you. acts 13:40<
Paul was just one of the messengers.