Characteristics of false teachers according to 2 Peter:
False prophets bring in damnable heresies
Deny the Lord that bought them
Speak evil of truth
Covetousness
Walk after the flesh in the lust of uncleanness
Despise government
Selfwilled
They are not afraid to speak evil of dignities
Speak evil of the that which they do not understand
Take pleasure in riots
Eyes full of adultery
Cannot cease from sin
Speak of vanity
Allure through the lusts of the flesh
Promise liberty, but are the servants of corruption
This lists helps us to recognize false teachers today. They will not be following the commandments. They will encourage sin. They themselves will be unable to resist temptation. They will preach against our savior.
The dangers of returning to the pollutions of the world after having the gospel and truth in your life is great. 2 Peter 2:21 says that it would have been better for them to not “have known the way of righteousness, than, after they have known it, to turn from the holy commandment delivered unto them”. It would be better to never know the truth and to remain in sin, than to have come from sin, and known truth, and then turn to sin again. It is like a dog turned to his own vomit.
D&C 82:3 says “for of him unto whom much is given much is required; and he who sins against the greater light shall receive the greater condemnation.” In verse seven is goes on to say that “ I, the Lord, will not lay any sin to your charge; go your ways and sin no more; but unto that soul who sinneth shall the former sins return, saith the Lord your God.”