John Calvin Commentary 1 Timothy 4:2

"through the hypocrisy of men that speak lies, branded in their own conscience as with a hot iron;" — 1 Timothy 4:2 (ASV)

Speaking lies in hypocrisy: if these words refer to “demons,” then this phrase signifies men deceiving through the instigation of the devil. But we may also interpret it as referring to “men speaking.” He now turns to a particular instance, when he says that they speak lies in hypocrisy, and have their conscience seared with a hot iron.

And indeed, it should be known that these two are so closely joined together that the former springs from the latter. For consciences that are bad and seared with the hot iron of their crimes always flee to hypocrisy as a ready refuge. That is, they contrive hypocritical pretenses in order to dazzle the eyes of God. And what else is done by those who endeavor to appease God with the mask of outward observances?

The word hypocrisy must therefore be explained in accordance with the passage in which it now occurs. First, it must relate to doctrine. Next, it denotes that kind of doctrine which adulterates the spiritual worship of God by exchanging its genuine purity for bodily exercises. Thus, it includes all methods contrived by men for appeasing God or obtaining His favor. The meaning may be summarized as follows:

1. All who assume a pretended sanctimoniousness are led by the instigation of the devil, because God is never worshipped rightly by outward ceremonies; for true worshipers worship him in spirit and truth, (John 4:24).

2. This is a useless medicine by which hypocrites mitigate their pains, or rather a plaster by which bad consciences conceal their wounds, without any advantage, and to their utter destruction.