"I am that I am," was the glorious name under which God introduced Himself to Israel. God over all - none by searching could find Him out: He would be God, and take His own way and He would have mercy on whom He would have mercy, and would have compassion on whom He would have compassion. God is God.
"By the grace of God, I am what I am," was Paul's joy; it is mine: may it be thine, too. But, then, how different the force of the sentence when applied to Him and when applied to me. Compare word with word and you will see this only the more forcibly. And yet in both applications, the finger points out to reality, and what is - is owned, as being AS IT IS.
"God is God."
"And I am a poor sinner and nothing at all. But Jesus Christ is my all in all."
Never, until we get to reality - never, until we let things be as they are, can we possibly have rest.
And the beauty of the gospel is, that it puts God as God; and myself, just as I am, blessedly together, and appropriates all that He is to me, and identifies all that I am with Him according to the worth of the person and the work of the Lord Jesus Christ, and by the Spirit of God and of Christ.