...It is all of God. Man cannot save himself, and the Law of God cannot save him, because it is weak through the flesh, our flesh. And even if the salvation planned and prepared by God Himself had to depend upon our flesh - my faith, my holding on, my abiding, or anything else - it would fail. But, thank God, it does not depend upon us at any point; it is altogether from God: it is God's action upon us at any point; it is altogether from God: it is God's action from beginning to end. The God who saves us is the God who keeps. He keeps us, we are in His hands, it is God's action.
This is vital to the whole argument of the Apostle. You can not have assurance of salvation, you can not have certainty of your final glorification unless you realize that salvation is altogether of God..."
D. Martyn Lloyd-Jones, "Romans: Exposition of Chapter 7:1 - 8:4: The Law: Its Functions and Limits", (Comments on Romans 8:3-4)