Why did the Jerusalem church send Barnabas to Antioch?
The assembly in Jerusalem sent Barnabas to Antioch after hearing tidings of what was happening there, because Gentiles were involved and it seemed not right according to Jewish thinking. He was to check out the situation as emissaries would examine reported heresy.
Les explains that when the Jerusalem assembly heard tidings about Antioch, they reacted like a denominational headquarters hearing of heresy in a distant place: they sent emissaries to check it out. The issue was Gentiles, since Jewish thinking held that this was for the Jew only. So they sent Barnabas, “good old Barnabas,” to see what was being done, because it was not right according to Jewish thinking. Later, when Barnabas arrived and saw the grace of God, it showed God chooses the right man for the right place and time.
Then tidings of these things came unto the ears of the church which was in Jerusalem: and they sent forth Barnabas, that he should go as far as Antioch.