The Apostle Paul warned Timothy to be watchful for false teachers, mentioning two examples by name: “Hymenaeus and Philetus are of this sort” (II Tim. 2:17). These two men were apparently heretics known to Timothy. In two passages, I Tim. 1:19-20 (where only Hymenaeus is mentioned) and II Tim. 2:16-18, we are given what we might call the “A-B-Cs” of a heretic.
A) The Authority Rejected. They have rejected God and the authority of His Word. They have “strayed concerning the truth” (II Tim. 2:18), and replaced God’s inspired revelation with “profane and idle babblings” (II Tim. 2:16)–even going so far (in Paul’s example) as to say the resurrection is past (vs. 18).
B) The Behaviour Adopted. They have an ungodly lifestyle. They are profane and blasphemous, defaming the name of God and the things of God (I Tim. 1:20; II Tim. 2:16). They evidence a growing ungodliness in their lifestyle (II Tim. 2:16) and their conscience is seared–meaning they are reprobate and readily call white black, and black white (I Tim. 1:19; cf. Rom. 1:21, 32).
C) The Consequences Following. They lead others into error and on to destruction. Their message, finding a ready hearing in the hearts of some, “spreads like cancer” (II Tim. 2:17), and “they overthrow the faith of some” (II Tim. 2:18). (These who turn from the faith would seem to be those who have certain beliefs but have never experienced true saving faith, cf. Matt. 7:21-23; Lk. 8:6, 13; Jn. 8:31; I Jn. 2:19.)