This is now the second letter that I am writing to you, beloved. In both of them I am stirring up your sincere mind by way of reminder, that you should remember the predictions of the holy prophets and the commandment of the Lord and Savior through your apostles, knowing this first of all, that scoffers will come in the last days with scoffing, following their own sinful desires. They will say, "Where is the promise of his coming? For ever since the fathers fell asleep, all things are continuing as they were from the beginning of creation."
2 Peter 3:1-4
The theme of the final chapter is the doctrine of Christ's Second Coming. This, it would seem, was one of the main objects of the false teachers' contempt, and Peter is particularly anxious to remind his readers of the centrality of their blessed hope. This he does by bringing before them the fact that Christ's Coming in power and glory is witnessed to by both the prophets of the Old Testament and the apostles of the New. It is important to realise this. The doctrine of the Return of Christ is not something that has been 'stuck on' to the gospel story as a kind of 'happy ending', it belongs to the very essence of the divine revelation, so much so, in fact, that apart from it, the gospel does not make sense. According to New Testament teaching, full salvation is not yet; we are saved in hope. But if Christ is not to come again, salvation will be not ever! It is as categorical as that! Even a cursory reading of a passage such as Romans 8:18-25 makes it plain that for the Christian everything depends on the prospect of Christ's coming again. It is the ground of his hope and confidence, and also of his optimism and peace: To challenge this doctrine is to call in question the entire gospel. This is the reason for Peter's concern.