Genesis 14:19

19.And he blessed him. Unless these two members of the sentence, ‘He was the priest of God,’ and ‘He blessed,’ cohere together, Moses here relates nothing uncommon. For men mutually bless each other; that is, they wish well to each other. But here the priest of God is described, who, according to the right of his office, sanctifies one inferior and subject to himself. For he would never have dared to bless Abram, unless he had known, that in this respect he excelled him. In this manner the Levitical priests are commanded to bless the people; and God promises that the blessing should be efficacious and ratified, (Numbers 6:23.) So Christ, when about to ascend up to heaven, having lifted up his hands, blessed the Apostles, as a minister of the grace of God, (Luke 24:51;) and then was exhibited the truth of this figure. For he testifies that the office of blessing the Church, which had been adumbrated in Melchizedek, was assigned him by his Father.

Blessed be Abram of the most high God. The design of Melchizedek is to confirm and ratify the grace of the Divine vocation to holy Abram; for he points out the honor with which God had peculiarly dignified him by separating him from all others, and adopting him as his own son. And he calls God, by whom Abram had been chosen, the Possessor of heaven and earth, to distinguish him from the fictitious idols of the Gentiles. Afterwards, indeed, God invests himself with other titles; that, by some peculiar mark, he may render himself more clearly known to men, who, because of the vanity of their mind, when they simply hear of God as the Framer of heaven and earth, never cease to wander, till at length they are lost in their own speculations. But because God was already known to Abram, and his faith was founded upon many miracles, Melchizedek deems it sufficient to declare that, by the title of Creator, (366) He whom Abram worshipped, is the true and only God. And although Melchizedek himself maintained the sincere worship of the true God, he yet calls Abram blessed of God, in respect of the eternal covenant: as if he would say, that, by a kind of hereditary right, the grace of God resided in one family and nation, because Abram alone had been chosen out of the whole world. Then is added a special congratulation on the victory obtained; not such as is wont to pass between profane men, who puff each other up with inflated encomiums; but Melchizedek gives thanks unto God, and regards the victory which the holy man had gained as a seal of his gratuitous calling.