John Calvin on Acts 6:12-13

12. Being overcome with the power of the Spirit, they give over disputing, but they prepare false witnesses, that with false and slanderous reports, they may oppress him; whereby it appeareth that they did strive with an evil conscience. For what can be more unmeet than in their cause to lean unto lies? “Quam in mendaciis causae suae praesidium constituere,” than to place the defense of their cause in lies. Admit he were a wicked man, and guilty, yet he must not have false witness borne against him. “Non tamen falsis testimoniis est oppremendus,” he ought not to be borne down with false testimony. But hypocrites, which shroud themselves under zeal, do carelessly grant themselves leave to do that. We see how the Papists at this day corrupt manifest places of Scripture, and that wittingly, whilst that they will falsely wrest testimonies against us. I confess, indeed, that they offend for the most part through ignorance; yet can we find none of them which doth not grant himself liberty to corrupt both the sense and also the words of the Scripture, that they may bring our doctrine into contempt; “Ut doctrinam nostram reddant odiosam,” that they may bring odium on our doctrine. yea, they slander us monstrously even in the pulpit. If you ask these Rabbins, whether it be lawful to slander a man or no, they will deny that it is lawful generally; but when they come unto us, good zeal doth excuse them, because they think that nothing is unlawful which may burden us or our cause; therefore they flatter themselves in lying, falsehood, and dogged impudence. Such hypocrisy did also blind them of whom Luke speaketh in this place, which used false witness to put Stephen to death; for when Satan reigneth, he doth not only prick forward the reprobate unto cruelty, but also blind their eyes, so that they think that they may do whatsoever they will. We are specially taught by this example, how dangerous the color of good zeal is, unless it be governed by the Spirit of God; for it breaketh out always into furious madness, and, in the mean season, it is a marvelous visor to cover all manner of wickedness.