John Newton knew what it meant to be a saint and a sinner at the same time. Here’s part of a letter he wrote to a Christian friend in April 1776:
I do not ask you if you are always filled with sensible comfort; but do you find your spirit more bowed down at the feet and will of Jesus, so as to be willing to serve him for the sake of serving him, and to follow him, as we say, through thick and thin; to be willing to be anything or nothing, so that he may be glorified?
I could give you plenty of good advice upon this head [topic], but I am ashamed to do it, because I so poorly follow it myself. I want to live with him by the day, to do all for him, to receive all from him, to possess all in him, to live all to him, to make him my hiding-place and my resting-place. I want to deliver up that rebel Self to him in chains; but the rogue, like Proteus, puts on so many forms, that he slips through my fingers: but I think I know what I would do if I could fairly catch him.
My soul is like a besieged city: a legion of enemies without the gates, and a nest of restless traitors within that hold a correspondence with them without – so that I am deceived and counteracted continually… Indeed it is a miracle that I still hold out. I trust, however, I shall be supported to the end, and that my Lord will at length raise the siege, and cause me to shout deliverance and victory.