2 Peter 2:15

forsaking the right way, they went astray, having followed the way of Balaam the son of Beor, who loved the hire of wrongdoing;

This clears up exactly the identity of the "cursed children" just mentioned. They were those who once were in the right way and then forsook it, who were lured from the path of duty by the wages of wrong-doing. The example selected by Peter to illustrate this departure is also eloquent in explaining the true meaning. Balaam was not always a false prophet; because, at one time, he was a genuine prophet of God, one of the great Messianic prophecies of the Old Testament being accredited to him:

There shall come a Star out of Jacob, and a scepter shall rise out of Israel, and shall smite the corners of Moab, and destroy all the children of Sheth (Numbers 24:17).

Peter's choice of Balaam, once a true prophet of God, but later an apostate, is absolutely analogous to the apostate teachers, once true children of God, later "cursed children," makes the meaning certain.

Who loved the hire of wrong-doing ... The story is set forth fully in the Book of Numbers, detailing how Balaam, for the love of reward, attempted to curse Israel for the king of Moab.

The choice of Balaam is most appropriate in still another particular. Finding it impossible to curse Israel, despite every effort to do so, Balaam originated the evil advice which he gave to Balak, and which eventually was the undoing of Israel. He advised the temptation of the Israelites to commit adultery, a temptation to which they succumbed (Numbers 31:16). Due to the extremely licentious character of the apostate teachers, Balaam was the perfect illustration of them.