John Calvin Commentary Acts 11:22

"And the report concerning them came to the ears of the church which was in Jerusalem: and they sent forth Barnabas as far as Antioch:" — Acts 11:22 (ASV)

And the tidings. If this report had been brought before Peter excused himself, those good men would have been reproved by many whose ministry God had nevertheless sealed with the grace of His Spirit; but that superstition was now wiped away from their minds, since God had by evident signs declared that no nation ought to be considered profane.

Therefore, they contend no longer, nor do they consider it an act of rashness that some dared to preach Christ to the Gentiles; but by sending help, they testify that they approve of what they had done. Furthermore, this was the reason they sent Barnabas.

The apostles at that time bore all the burden of the kingdom of Christ. Therefore, it was their duty to frame and set in order Churches everywhere, to keep all the faithful, wherever dispersed, in the pure consent of faith, and to appoint ministers and pastors wherever there was any number of the faithful.

The crafty wiliness of Satan is well known. As soon as he sees a gate set open for the gospel, he endeavors by all means to corrupt what is sincere [pure]; as a result, various heresies broke out together with Christ’s doctrine.

Therefore, the greater gifts every Church has, the more careful it ought to be, lest Satan mix or trouble anything among the ignorant and those who are not yet established in the right faith, because it is the easiest thing in the world to corrupt corn in the blade.

To conclude, Barnabas was sent to bring them further forward in the principles of faith, to establish some order, and to give the building that was begun some form, so that there might be a lawful state of the Church.