John Calvin Commentary Acts 8:20

"But Peter said unto him, Thy silver perish with thee, because thou hast thought to obtain the gift of God with money." — Acts 8:20 (ASV)

Peter answered. Peter firmly repulses him here, and not content to merely chide him, he adds a bitter curse (or wish), that Simon and his money might perish together; though he does not so much wish destruction upon him as tell him that the just vengeance of God hangs over his head, so that he might terrify him.

In sum, he shows what Simon has deserved, since he has made the Spirit of God subject to filthy buying and selling; as if he were saying, "You are worthy to perish with your money, since you so blaspheme the Spirit of God." For we may easily gather from what follows, that Peter would rather have had Simon saved than destroyed.

But, as it were, occupying the place of a judge, he pronounces what punishment Simon’s ungodliness deserves; and it was necessary that Simon should be accused with such vehemence, so that he might perceive the greatness of his offense. His judgment that Simon's money should perish serves the same end, for he signifies that it was, as it were, infected and polluted with wicked thoughts, because it was offered for such a wicked use.

And surely, we ought rather to wish that the entire world perish than that those things, which are worthless in comparison, should darken the glory of God. When Peter makes such a wish towards a sacrilegious man, he does not so much consider the person as the deed; for we must be offended by the offenses of men in such a way that we still pity the men themselves.

Such are those sentences of God which condemn adulterers, thieves, drunkards, and wrongdoers to destruction (1 Corinthians 6:9; Ephesians 5:5), for these sentences do not cut off all hope of salvation from them. Instead, they refer only to their present state and declare what end is prepared for them if they continue obstinately.