This verse has a great deal of similarity with Jude 11.

Forsaking the right way they have gone astray is related to “Balaam’s error” in Jude 11. Right is used here in the sense of “correct,” “right,” “true.” Way is literally a road, but it is also used metaphorically to mean “a course of conduct,” “a way of doing things.” In the Bible “straight path” (Good News Translation) is used to describe proper and upright conduct (see 1 Sam 12.23; Hos 14.9; Acts 13.10). Some have taken the right way here as equivalent in meaning to “the way of truth” in 2 Peter 2.2 (for which see discussion there). Other ways of expressing the right way are “behave in a just or righteous way,” “have good conduct,” or “walk good lives.”

Forsaking can also be “They have abandoned” (New English Bible). It is a present participle in the Greek, but most modern translations understand it to function as a perfect tense, “having forsaken.” It may be simply translated as a perfect verb, which is what Revised Standard Version and Good News Translation (and most translations) have done. Forsaking the right way may also be expressed as “They have left the way of righteousness,” “They have stopped doing good,” “Their conduct has become evil,” or “They no longer walk good lives.”

The result of all this is that the false teachers have gone astray, a most logical conclusion. This expression is used figuratively here to mean they have been corrupted both spiritually and morally; they have accepted and followed doctrines and disciplines of life that led them to reject God rather than trust in him. In some languages this may be translated as “their hearts have become corrupt (or, evil),” or “they do evil things.”

So, instead of following the right way, they follow the way of Balaam, the son of Beor. Balaam is also mentioned in Jude 11. In the Old Testament Balaam’s father is named “Beor” (see Num 22.5; 24.3, 15), which explains why “Beor” is the form in many of the Greek manuscripts. It is very likely, however, that the variant form “Bosor” is the original in the Greek. In any case, rendering “Bosor” as “Beor” is justified here on the principle of using only the more common name when someone or something is known by two or more names. The clause they have followed the way of Balaam may be expressed as “They have done exactly what Balaam … did,” “They have imitated Balaam…,” or “They have followed the example of Balaam….”

The way of Balaam is not explained any further; there are three suggested possible points of comparison: greed, leading people to sin, and claiming to be God’s prophet or teacher. Perhaps the first of these, namely “greed,” is the most probable point of comparison, since it is mentioned in verse 14. This also fits what follows, since Balaam is described as one who loved gain from wrongdoing. We are told in the Old Testament that it was love of money that caused Balaam to lead Israel to sin (see Num 22-24; 31.16, and especially Jude 11 for further discussion of Balaam). In certain languages gain will need to be rendered as “the money he would be paid,” or in the active as “the money they would pay him.”

An alternative translation model for this verse is:
• They have stopped doing good and turned to evil ways (or, their hearts have become corrupt). They have followed the example of Balaam, who loved the money people would pay him for doing evil.

Quoted with permission from Arichea, Daniel C. and Nida, Eugene A. A Handbook on The Second Letter from Peter. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .