So Paul appears to be alluding to a tradition that these two men, Jannes and Jambres, did magic. They were evil men who were against the truth of God. They opposed Moses and Aaron whom God sent to free the Jews from Egypt. Paul says that the false teachers are just like those evil men. What they were doing was not identical but, like those men, they are enemies of the truth. In the final analysis, they are working against God. They have believed a lie and there is no truth with them. The evil which they have accepted has ruined them. Their minds have become wicked. They can no longer know what is true or receive it. They have denied the truth of God.
Sometimes it looks as though the pedlars of error are winning, they may seem to succeed. But that success will not last long. The truth will win in the end. In due time, all will see the true character of these teachers. They are utterly foolish to oppose the truth.
Paul spares no blushes attacking these teachers of error. He say that these heretics “resisted the truth” and were men “of corrupt minds”, whose understanding was perverted, biased and prejudiced against the truth; they are “reprobate concerning the faith” – the term means castaway, rejected, concerning the true faith – in other words, they are very far from being true Christians. Heresy cannot be tolerated. There is no middle ground. When truth is rejected, those who preach error are, and will be, rejected.