Luke
Acts 15:1ESV·traditional attribution

But some men came down from Judea and were teaching the brothers, “Unless you are circumcised according to the custom of Moses, you cannot be saved.”

John Calvin Reformed @genevareformer

1. When Paul and Barnabas had endured many combats against the professed enemies of the gospel, Luke doth now begin to declare that they were tried by domestic war; so that it was meet that their doctrine and ministry should be proved by all means, to the end it might the better appear that they were furnished by God, and armed against all the assaults of the world and Satan.

Matthew Henry Presbyterian @wholebiblehenry

Even when things go on very smoothly and pleasantly in a state or in a church, it is folly to be secure, and to think the mountain stands strong and cannot be moved; some uneasiness or other will arise, which is not foreseen, cannot be prevented, but must be prepared for.

Commenting on Acts 15:1-5

Albert Barnes Presbyterian @notesbybarnes

CHAPTER 15 Verse 1. And certain men. These were men undoubtedly who had been Jews, but who were now converted to Christianity. The fact that they were willing to refer the matter in dispute to the apostles and elders, , shows that they had professedly embraced the Christian religion. The account which follows is a record of the first internal dissension which occurred in the Christian church.