Genesis 3:22 - Matthew Poole's English Annotations on the Holy Bible

The Lord God said, either within himself, or to the other persons of the Godhead, Adam and Eve both are become such according to the devil's promise, and their own expectation. This is a holy irony, or sarcasm, like those, 1 Kings 18:27 Ecclesiastes 11:9: q.d. Behold! O all ye angels, and all the future generations of men, how the first man hath overreached and conquered us, and got the Divinity which he affected; and how happy he hath made himself by his rebellion! But this bitter scorn God uttereth not to insult over man's misery, but to convince him of his sin, folly, danger, and calamity, and to oblige him both to a diligent seeking after, and a greedy embracing the remedy of the promised Seed which God offered him, and to a greater watchfulness over himself, and respect to all God's commands for the time to come. As one of us, i.e. as one of the Divine persons, of infinite wisdom and capacity. Here is an evident proof of a plurality of persons in the Godhead; compare Genesis 1:26, and Genesis 11:7. If it be said, God speaks this of himself and the angels; besides that as yet not one word hath been spoken concerning the angels, it is an absurd and unreasonable conceit that the great God should level himself with the angels, and give them a kind of equality with himself, as this expression intimates. To know all things, both good and evil. Lest he put forth his hand: the speech is defective, and to be supplied thus, or some such way. But now care must be taken, or man must be banished hence, lest he take also of the tree of life, as he did take of the tree of knowledge, and thereby profane that sacrament of eternal life, and fondly persuade himself that he shall live for ever. This is another scoff or irony, whereby God upbraideth man's presumption, and those vain hopes wherewith he did still feed himself.