John Calvin Commentary Acts 7:58

"and they cast him out of the city, and stoned him: and the witnesses laid down their garments at the feet of a young man named Saul." — Acts 7:58 (ASV)

They stoned. God had appointed this kind of punishment in the Law for false prophets, as it is written in Deuteronomy 13; but God also defines there who should be considered in that number—namely, one who attempts to lead the people to strange gods. Therefore, the stoning of Stephen was both unjust and wicked, because he was unjustly condemned. Thus, the martyrs of Christ must suffer the same punishment as the wicked.

It is the cause alone that makes the difference; but this difference is so highly esteemed by God and His angels that the rebukes of the martyrs far excel all the glory of the world.

Yet here a question may be raised: How was it lawful for the Jews to stone Stephen, since they did not have the governing authority in their hands? For in Christ’s case, they answer, It is not lawful for us to put any man to death. I answer that they did this violently and in an uproar. And since the governor did not punish this wickedness, it may be that he winked at many things, so that they would not bring upon his own head the hatred they bore against the name of Christ. We see that the Roman governors often winked at the civil discords of that nation, even deliberately, so that when its people murdered one another, they might be more easily overcome afterward.