If they have escaped the corruption of the world by knowing our Lord and Savior Jesus Christ and are again entangled in it and overcome, they are worse off at the end than they were at the beginning. (2 Pet 2:20)
Verse 20 also shows the word they refer to the false teachers, who will deceive many Christians with their empty presentations about freedom and grace, as related to the Christian life. This same verse also shows they too were once freed from the entanglement and slavery of sin, which happens at initial salvation (getting born again) for all people.
It would have been better for them not to have known the way of righteousness than to have known it and then to turn their backs on the sacred command that was passed on to them. (2 Pet 2:21)
Again, it is clear that such false teachers in the church were once saved, but now are worse off than would be the case if they had never been saved! They once knew the Lord but turned their backs on the sacred command. So what is the sacred command? John narrows God’s commandments into one broad command: And this is His command:
To believe in the name of His Son, Jesus Christ, and to love one another as He commanded us. (1 John 3:23)
It is impossible to believe in Jesus if one is not OBEYING Him just like it is also impossible to love a person if one is not trying to protect him/her from the hurtful effects of false doctrine.
There used to be false prophets in the past among God’s people. And there will be false teachers among you. They will secretly teach wrong things about God that will ruin people. The false teachers will refuse to accept their masters who bought them. And so, they will quickly destroy themselves.
Many of them will follow their own evil ways. Because of this, other people will say evil things about the true Christian way. These false teachers only want your money. They will make a profit from you when they tell you untrue stories. A long time ago, God judged them. And He will destroy them at some time in the future. 2 Peter 2:1-3