This New Testament picture of life is that it is the scene of a mighty, terrible, spiritual struggle and conflict. Read anywhere in this Book, read the words of our Lord as recorded, read the sermons of the first preachers as you find them in the Acts of the Apostles, read any one of these Epistles you may choose, staring with the Epistle to the Romans, and going right on through to the Book of Revelation; everywhere you are given a sense of crisis, a sense of judgment. Life in this world, according to this Book (and the same thing is equally true of the Old Testament) is the scene of a mighty, terrible conflict between two vast powers. And they are both spiritual powers – God and all His forces on the one hand, and Satan, the Devil, and all his forces on the other. And, according to this Book, what happens in this life and in this world is that these two mighty powers and forces are both engaged in trying to win the suffrage of man, trying to attract man, trying to win man to their respective sides. This terrible, mighty conflict is going on. The result is that there is never any easy optimism to be found in the New Testament; there is no vague general superficiality. All along, its message is one of preparing us for this conflict, of enabling us to realize the nature of the conflict. It will not allow us to escape; indeed, its great theme is that the one great danger is that we allow the world in various ways to make us forget it.
– Martin Lloyd-Jones, Expository Sermons on 2 Peter, p. 124.