In this chapter Peter sketches the character, motives, and appeal of false teachers who threaten the church from within. Their character is seen in their bold, arrogant contempt for authority and exploitation of others. Their motives are revealed in their greed and sexual immorality. Their appeal is to man's baser nature, with promises of a freedom that releases all restraint and results in captivity to sin. The false teacher appeals to many because he seems attractive, strong, and confident. Few resent the material prosperity he craves, for he seems to them deserving of God's blessing. And many respond to his promises of health, material blessing, and freedom from the ills that all human beings are heir to in this sinful world. What a contrast with the servant of God, who all too often seems weak and struggling. Rather than a life of ease, Peter calls Christians to servanthood and even suffering. Bible Reader's Companion.
In trying to discern who is a false teacher and who is not, a believer's best defense is to know the truth. If we have added to our faith, knowledge then that knowledge of what is true will quickly show up the lies and deceit of false teachers. Get to know the truth and allow that to be the measure by which you discern if a teacher is false or not.