“The truth and certainty of this blessed state are ratified by the word and promise of God, and ordered to be committed to writing, as matter of perpetual record, Revelation 21:5,6. The subject-matter of this vision is so great, and of such great importance to the church and people of God, that they have need of the fullest assurances of it; and God therefore from heaven repeats and ratifies the truth thereof. Besides, many ages must pass between the time when this vision was given forth and the accomplishment of it, and many great trials must intervene; and therefore God would have it committed to writing, for perpetual memory, and continual use to his people. Observe, 1. The certainty of the promise averred: These words are faithful and true; and it follows, It is done, is as sure as if it were done already. We may and ought to take God’s promise as present payment; if he has said that he makes all things new, it is done. 2. He gives us his titles of honour as a pledge or surety of the full performance, even those titles of Alpha and Omega, the beginning and the end. As it was his glory that he gave the rise and beginning to the world and to his church, it will be his glory to finish the work begin, and not to leave it imperfect. As his power and will were the first cause of all things, his pleasure and glory are the last end, and he will not lose his design; for then he would no longer be the Alpha and Omega. Men may begin designs which they can never bring to perfection; but the counsel of God shall stand, and he will do all his pleasure. 3. The desires of his people towards this blessed state furnish another evidence of the truth and certainty of it. They thirst after a state of sinless perfection and the uninterrupted enjoyment of God, and God has wrought in them these longing desires, which cannot be satisfied with any thing else, and therefore would be the torment of the soul if they were disappointed but it would be inconsistent with the goodness of God, and his love to his people, to create in them holy and heavenly desires, and then deny them their proper satisfaction; and therefore they may be assured that, when they have overcome their present difficulties, he will give them of the fountain of the water of life freely.”

-Matthew Henry