[I AM is a] name that denotes what he is in himself: ‘I am [who] I am’. This explains his name Jehovah, and signifies…
That he is self-existent; he has his being of himself, and has no dependence upon any other: the greatest and best man in the world must say, By the grace of God I am what I am; but God says absolutely—and it is more than any creature, man or angel, can say—I am [who] I am. Being self-existent, he cannot but be self-sufficient, and therefore all-sufficient, and the inexhaustible fountain of being and bliss.
[And] he is eternal and unchangeable, and always the same, yesterday, today, and for ever; he will be what he will be and what he is; [‘the Lord God who is, who was, and who is to come’ (Revelation 1:18)]
[… And then, finally,] that he is faithful and true to all his promises, unchangeable in his word as well as in his nature, and not a man that he should lie.
This is the “I AM” who we meet in John 6:20.
