This OP is for attempting a combined participation from those who are desiring to know more about the permanency of faith and salvation. I am presenting a couple passages to attempt to initiate interest in others who might desire to list whatever passages they can find relating to this issue that we can analyze together. The reason for my interest in dealing more with this issue is due to the fact that I believe it is the most significant Bible doctrine related to spiritual growth in the “image of Christ.”
2Pet 2:20
“For if, after they have escaped the pollutions of the world through the knowledge of the Lord and Savior Jesus Christ . . .” They can obtain mental peace (escape) merely through knowing (but not understanding) Christ’s Gospel and acting in outward motions of false professions and works, but if they have not truly desired to be in His Gospel it will eventually manifest itself when “they are again entangled in them and overcome.”
2Pe 2:21
“For it would have been better for them not to have known the way of righteousness, than having known it, to turn from the holy commandment delivered to them.” This describes only “knowing the way,” but instead of following it they “turn from it,” and continue as they were.
This parallels Heb 10:26: “For if we sin willfully after that we have received the knowledge of the truth . . .” (Heb 10:26). Both of these passages are a description of one merely receiving the knowledge of the truth but not receiving the “truth.” In other words, choosing to continue as they were, even after becoming aware of “the truth,” but not choosing to receive and follow it.
A Couple Commentator Examples:
Albert Barnes (1798–1870):
“For if after they have escaped the pollutions of the world” - This does not necessarily mean that they had been true Christians, and had fallen from grace. People may outwardly reform, and escape from the open corruptions which prevail around them, or which they had themselves practiced, and still have no true grace at heart.
“Through the knowledge of the Lord and Savior Jesses Christ” - Neither does this imply that they were true Christians, or that they had ever had any saving knowledge of the Redeemer. There is a knowledge of the doctrines and duties of religion which may lead sinners to abandon their outward vices, which has no connection with saving grace. They may profess religion, and may know enough of religion to understand that it requires them to abandon their vicious habits, and still never be true Christians.
“For it had been better for them …” It would have been better for them, for:
(1) Then they would not have dishonored the cause of religion as they have now done.
(2) They would not have sunk so deep in profligacy as they now have.
(3) They would not have incurred so aggravated a condemnation in the world of woe. If people are resolved on being wicked, they had better never pretend to be good. If they are to be cast off at last, it had better not be as apostates from the cause of virtue and religion.
2 Peter 2 Commentary - Albert Barnes' Notes on the Whole Bible
John Gill (1697–1771):
“For if after they have escaped the pollutions of the world....” The sins of it, the governing vices of it, which the men of the world are addicted to, and immersed in; for the whole world lies in wickedness, and which are of a defiling nature: the phrase is Rabbinical; it is said {q}, "he that studies not in the law in this world, but is defiled amle ypwnjb, "with the pollutions of the world," what is written of him? and they took him, and cast him without:" these, men may escape, abstain from, and outwardly reform, with respect unto, and yet be destitute of the grace of God; so that this can be no instance of the final and total apostasy of real saints; for the house may be swept and garnished with an external reformation; persons may be outwardly righteous before men, have a form of godliness and a name to live, and yet be dead in trespasses and sins; all which they may have
“Through the knowledge of the Lord and Savior Jesus Christ.” The Vulgate Latin, and all the Oriental versions, read, our Lord, and the latter leave out, "and Savior"; by which "knowledge" is meant, not a spiritual experimental knowledge of Christ, for that is eternal life, the beginning, pledge, and earnest of it; but a notional knowledge of Christ, or a profession of knowledge of him, for it may be rendered "acknowledgment"; or rather the Gospel of Christ, which, being only notionally received, may have such an effect on men, as outwardly to reform their lives, at least in some instances, and for a while, in whose hearts it has no place.
“For it had been better for them....” Not that ignorance is good, or to be excused; but it would have been a lesser evil, and not so much aggravated:
Not to have known the way of righteousness; the same with "the way of truth," 2 Peter 2:2, and "the right way," 2 Peter 2:15, the Gospel, which points out the way and method of a sinner's justification before God, which is not by the works of the law, but by the righteousness of Christ imputed to them, and received by faith; and which teaches men to live soberly, righteously, and godly; and a large, notional, though not an experimental knowledge, these apostates had of the word and doctrine of righteousness, and indeed of the whole of the Christian religion, which may truly go by this name:
Than after they have known [it]; owned, embraced, and professed it:
To turn: the Vulgate Latin version, and some copies, as the Alexandrian and others, add, to that which is behind; to their former lusts, or errors, or worse, which they had turned their backs upon externally.
From the holy commandment delivered unto them; by the commandment is meant the Gospel also, see 2 Peter 3:2; called holy, because of its nature and influence, and in opposition to the pollutions of the world; and which is the faith once delivered, Jude 1:3, and which they received, as delivered to them; and, particularly, the ordinances of it, which they once submitted to, kept, and observed, as they were delivered to them, but now relinquished, or corrupted: wherefore, it would have been better for them to have been in their former ignorance, either in Judaism, or in Gentilism, since proportionate to a man's light is his guilt, and so his punishment, see Romans 2:12.
2 Peter 2 - John Gill’s Exposition of the Bible - Bible Commentary