Deuteronomy 32 is called the Song of Moses. It is a song that was intended to warn Israel through the ages of the consequences of apostasy and disobedience to God.
“For whatever overcomes a person, to that he is enslaved. For if, after they have escaped the defilements of the world through the knowledge of our Lord and Savior Jesus Christ, they are again entangled in them and overcome, the last state has become worse for them than the first” (2 Peter 2:19-20, ESV).
Peter speaks here of false teachers who “bring in destructive heresies” (II Peter 2:1) and the people they lead astray with these detrimental teachings. If you succumb to these false teachings or their teacher, then you are a slave to whatever is controlling you.