The Jewish writers interpreted it to mean, "I am he that was, I am he that is now, and I am he that is to come and shall be." The Lord God describes himself in exactly that same way in both the Old and New Testaments (Isa. 43:13; Rev.1:4, 8). The marginal translation of Exodus 3:14 is, "I save in the manner in which I will save," revealing both the goodness of God in choosing to save and his sovereignty in reserving to himself the right to save whom he will, as he will. John Gill says, I AM "seems to be of the same signification with Jehovah, and to be derived from the same word, and is expressive of the same things: of the Being and existence of God, of his eternity and immutability, and of his faithfulness in performing his promises."
When the Lord God calls himself I AM, he declares himself to be the eternal, unchanging, unchangeable, constant, and faithful; the infinite God who comprehends all things, all time, and all space, past, present, and future, but is comprehended of nothing. This name means, according to one, "I am what I am, I am what I have been, I am what I shall be, and I shall forever be what I am."
If any should assume this title and call himself, I AM, he is either the greatest, most vile blasphemer imaginable or he is, in fact, God over all and blessed forever. The Lord Jesus Christ did just that. He said, "Verily, verily I say unto you, before Abraham was I AM," thereby avowing himself to be very God of very God who has come to save his people from their sins.