John Calvin Commentary 1 Timothy 6:21

"which some professing have erred concerning the faith. Grace be with you." — 1 Timothy 6:21 (ASV)

Which some professing, have erred concerning the faith. From the result, he also demonstrates how dangerous such a thing is, and how much it should be avoided. The way God punishes the haughtiness of those who, through the desire to obtain a reputation, corrupt and disfigure the doctrine of godliness, is that he allows them to fall away from sound understanding, so that they involve themselves in many absurd errors.

We see that this has taken place in Popery; for, after they began to speculate in a profane manner about the mysteries of our religion, there followed innumerable monsters of false opinions.

Faith is here taken, as in some former passages, to mean the summary of religion and sound doctrine. Warned by such examples, if we abhor revolt from “the faith,” let us adhere to the pure word of God, and let us detest sophistry and all useless subtleties, because they are abominable corruptions of religion.