Now as Jannes and Jambres withstood Moses, so do these also resist the truth: men of corrupt minds, reprobate concerning the faith. II Tim. 3:8
Jannes and Jambres were the two famous Egyptian magicians who opposed Moses, and in a few instances duplicated his wonders in the presence of Pharaoh.
These men were highly versed in Egyptian magic and sleight of hand. After enchanting, they cast down their rods, which they turned into serpents (Exod. 7:11-12). They also, like Moses, smote the river and turned its water into blood (Exod. 7:22). With their highly developed art of magic they succeeded in belittling Moses’ miracles and wonders and thus hardened Pharaoh’s heart.
These apostates who had left the Christian faith and were opposed to Paul, he likened to the wise men of Egypt who had been successful in opposing Moses. The apostates had caused considerable strife in the churches and led many people astray from the truth of Christ. As a result, others were deserting Paul (II Tim. 1:15). Even some of his close disciples and followers had already left the church. Paul complained strongly against these unfaithful men (II Tim. 4:10-16).
Many of the religions in Asia Minor were introduced from Egypt and Babylon. The priests of these religions studied magic. Christian converts were still under the influence of the teachings of the pagan religions which surrounded them. Then again, it must be remembered that the Christian flock was very small and insignificant in a world where pagan religions exerted such great social and political influence. In other words, the pagan religions offered more material gains and opportunities than Christianity. The Christians, at the outset, were told to expect persecution and to be ready to die if necessary for the gospel that had been delivered to them. Nevertheless, some converts failed to remain steadfast. The temptations of the world about then made them deny Christ.
(Lamsa, George. New Testament Commentary, A.J. Holman Co., Philadelphia: 1945, pgs 435-436)