From the Reformer
Simon answered. Hereby we gather that he did not so take that which Peter had threatened unto him, but that he did consider that his salvation was sought. And though Peter alone spake, yet he attributeth the speech unto all by reason of the consent. Now ariseth a question what we ought to think of Simon. The Scripture carrieth us no farther, save only unto a conjecture. Whereas he yieldeth when he is reproved, and being touched with the feeling of his sin, feareth the judgment of God; and that done, flieth unto the mercy of God, and commendeth himself to the prayers of the Church; these are assuredly no small signs of repentance; therefore we may conjecture that he repented. And yet the old writers affirm with one consent, that he was a great enemy to Peter afterward, and that he disputed with him by the space of three days at Rome. The disputation is also extant in writing under the name of Clement, but it hath in it such filthy dotings, that it is a wonder that Christian ears can abide to hear them. Again, Augustine, writing to Januarius, saith, that there were divers and false rumors spread abroad in Rome in his time concerning that matter. Wherefore, nothing is more safe than bidding adieu to uncertain opinions, simply to embrace that which is set down in the Scriptures. That which we read elsewhere of Simon may justly be suspected for many causes.
—John Calvin, Commentary on Acts
Pulling It Together
Simon had believed in the Lord but then continued in his wicked craft, mixing the devil with the Lord in his heart. These two cannot abide together long. Repentance is necessary. When rebuked by another Simon, scripture tells us that the sorcerer asked for prayers on his own behalf. This is a sign of repentance and much to his credit. Still, the Church has debated the genuineness of his repentance to the point we now call the selling of church offices, simony. Jesus had a teaching about this sort of debate: “Why do you see the speck that is in your brother’s eye, but don’t consider the beam that is in your own eye?” (Matt 7:3) Very often the bitter and sinful heart that needs to change is not the one you into which you are looking. If we spent less time conjecturing about the Simons around us, and more time looking into our own condition, we would see more clearly.