Summary of passage: A warning against false teachers who will secretly introduce destructive heresies, bringing destruction upon themselves. These teachers will exploit you out of greed and bring the truth into disrepute. Many will follow them but they will face destruction.
God did not spare angels, the ancient world of Noah, Sodom and Gomorrah so He won’t spare these ungodly teachers. The Lord will rescue righteous men like He did for Lot and punish the unrighteous.
These men are bold, arrogant, slander celestial beings, and blaspheme and they will perish. They will be paid back. They entice people by appealing to the lustful desires of sinful human nature and they promise freedom. It would have been better for them not to have known the Lord than to have known Him and turned their backs on him.
6a) Bar-Jesus (Acts 13:6-12) whom Barnabas and Saul/Paul met in Paphos. Paul temporarily blinded him with the power of the Holy Spirit. They are ultimately proven false by God for they cannot stand against His Truth. “For such people are not serving our Lord Christ, but their own appetites.” Romans 16:18
b) They will bring swift destruction and condemnation on themselves
7) Angels sent to hell (Jude 1:6; Revelation 20:1-2); Flooded the world (Genesis 7-8); condemned Sodom and Gomorrah and saved Lot (Genesis 19; Jude 1:7)
8a) By appealing to the lustful desires of sinful human nature, they entice people who are just escaping from those who live in error (believers escaping from unbelievers) and promising them freedom.
b) Personal Question. My answer: What Peter recommends in 2 Peter 1:5-8: strengthen my faith, goodness, knowledge, self-control, perseverance, godliness, brotherly kindness, and love. Pray. Read the Bible. Learn from other believers. Seek support. Act.
Conclusions: As a born skeptic (one who doesn’t believe anything is free in this life and if it sounds too good to be true it is), I would like to think it would be hard for me to be duped. But the devil is crafty and knows all of our weaknesses. That’s why it’s important to always be alert and watch out for the prowling lion (1 Peter 5:8; 1 Corinthians 16:13) and have on God’s armor (Ephesians 6). Be prepared to fight for the Truth and help others to do so as well.
The writer obviously despised false teachers by how he goes and on how vile they are and how they will pay in the end. They must have been doing great damage in his times.