Before I post some more scripture, here's some commentary on the 2Peter issue:
Commentaries are just that and not all commentators agree with your view.
Here is a sad proof of the possibility of falling from grace, and from very high degrees of it too.
"Sad proof" is debatable and you sound like the "tight rope walking 90% of all Christians will lose their salvation" proponent.
As I said before:
Those who are truly born of God have received a new nature, a divine nature, and they have new and different appetites and desires. They have been transformed from pigs and dogs into sheep. The change is more than just cosmetic, as in 2 Peter 2:20. *These cleaned up on the outside dogs and pigs were never sheep.
*Compare 2 Peter 1:4 -
"partakers of the divine nature," having escaped the
corruption - Strongs #5356 that is in the world through lust with 2 Peter 2:20 - with they escaped the
pollutions - Strongs #3356 (different Greek word) of the world through the knowledge of the Lord and Savior Jesus Christ, yet they are again entangled therein, and overcome. *Notice that 2 Peter 2:20
did not mention them being "partakers of the divine nature."
Corruption (Strongs #5356) (to shrivel or wither, spoil , ruin , deprave, corrupt , defile, to destroy by means of corrupting, to spoil as does milk). Corruption - describes decomposition or rotting of an organism and the accompanying stench. The utter depravity of the fallen flesh and the resultant moral decomposition of the world opposed to God is driven by it sinful lusts or evil desires.
Internal corruption.
Pollutions/Defilements (Strongs #3393) ("pollutions", "filthy things", "contaminations", "world's filth") describes the state of being tainted or stained by evil and refers to impurity, impure, tainted, defilement, foulness or pollution.
Pollutions/Defilement refers to what is on the outside (2 Peter 2:20). But genuine believers have escaped the "corruption that is in the world through lust" (2 Peter 1:4).
*Corruption is deeper than pollutions/defilements on the outside: it is
decay on the inside.
Having the knowledge of Jesus Christ does not save a person if there is
no heart submission to that knowledge. The latter end is worse than the beginning for these false teachers because rejecting this knowledge will make them more accountable at the judgment."
So who are "they" in verse 20? This is variously interpreted as either the false teachers or their victims, but the proximity to the false teachers in (2 Peter 2:19) makes them the most natural antecedent of "they". Furthermore, the false teachers are the main subject of the whole chapter. Peter did not mention that those who escaped the"pollutions of the world" through the knowledge of the Lord and Saviour Jesus Christ, were "Christians," "born of God" or "saved."
In conclusion: It's one thing to escape
corruption "phthora" (Strongs #5356) on the
inside in 2 Peter 1:4 and another thing to escape
pollutions/defilements "miasma" (Strongs #3393) on the
outside in 2 Peter 2:20. False teachers are the main subject in chapter 2. Did Peter refer to those in 2 Peter 2:20 as being "Christians," "born again" or "saved?" - NO. Did 2 Peter 2:20 mention being
"partakers of the divine nature?" - NO. Were the words "lost salvation" mentioned? - NO. Is the word corruption "phthora" (Strongs #5356) in 2 Peter 1:4 a different Greek word than pollutions/defilements "miasma" (Strongs #3393) in 2 Peter 2:20? - YES.
You can believe what you want, but as for me, I got off that roller coaster ride of fear and bondage to IN-secruity when I left the Roman Catholic church several years ago after I received Christ through faith. Praise God!