through the hypocrisy of men who speak lies, branded in their own conscience as with a hot iron;
Branded in their conscience as with a hot iron ... This is a description of the "hardened," "blinded," deadened soul in whom the truth principle has utterly perished.  It begins by rejecting what is known to be true, but in its progression it leaves the "deluded" totally without moral or spiritual guidelines.  The Scriptures contain a great deal of material on the judicial hardening of willful sinners; and those interested in further pursuit of the subject will find a discussion of it in my Commentary on Romans, pp. 392-395.