There is a distinct development in 1 John 5:18-20. As a general truth such is the characteristic of being born of God—such do not sin, and the wicked one has no hold on them, such being their nature. But further, 'We know that we are of God’—derive our nature from, and so are associated with Him. We affirm something about ourselves. It is not abstract as to a nature, but absolute contrast of nature and position as to ourselves—we are of God, the world is lying in the power of evil. But there is objective knowledge too—we know that the Son of God is come—we know Him that is true, and are in Him, even in His Son, and He is the true God. The contrast in verse 19, following on verse 18, is very absolute. It is not merely one born of God will not sin—a general truth—but the fact that we are of God and know it. The whole world is in exactly the opposite state—opposite essentially in condition and state. Besides that, we know the great truth of divine history, and we are in God by Him. Redemption, though clearly stated, is not the great subject of John, but life by resurrection—only we find it in resurrection.