Expositor's Bible Commentary 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)

The apostle uses strong language in describing the teachers of the false doctrines he is about to mention. He declares that they are “hypocritical liars”; this implies that they know better, but they have deliberately forsaken the faith and teach falsehood. They are people whose consciences “have been seared as with a hot iron,” so that they have become unfeeling about their willful wrongdoings.