Quote from David Pawson: Once Saved Always Saved? (p. 97)
False teachers can increase their credibility by quoting scriptures and claiming to explain the difficult passages, especially in Paul’s letters, which ‘ignorant and unstable people distort, as they do the other scriptures, to their own destruction’ (2 Peter 3:16). Note that Paul’s epistles are already classed as ‘scriptures’, alongside the Old Testament, by the time 2 Peter was written; and that some parts of them were already proving ‘hard to understand’! The closing exhortation is accordingly appropriate: ‘Therefore, dear friends, since you already know this, be on your guard so that you may not be carried away by the error of lawless men and fall from your secure position’ (2 Peter 3:17).