Why did the Grecians in Jerusalem try to kill Saul?
The Grecians—Jews from outside Palestine, not Gentiles—sought to kill Saul after he preached boldly in Jesus’ name and disputed with them in Jerusalem. Their hostility arose because they could not tolerate opposition to Judaism, and they believed killing the opponent was the way to remove it.
Les explains that the Grecians were not Gentiles but non-Palestine Jews—Jews who were citizens of other nations, not Palestine. Saul had been preaching boldly in the name of the Lord Jesus at Jerusalem and disputed against these Grecians. Because they could not stand anyone doing anything against Judaism, they sought to kill him. As Les puts it, nothing preempts murderous attitudes faster than religion; if they had opposition, the best way to get rid of it was to kill the opponent. So that is what they attempted with Saul.