Psalms 89:4

Let us see then what God has sworn. "I have sworn," He says, "to David My servant; your seed will I establish for ever" [Psalm 89:4]. But what is the seed of David, but that of Abraham. And what is the seed of Abraham? "And to your seed," He says, "which is Christ." [Galatians 3:16] But perhaps that Christ, the Head of the Church, the Saviour of the body, [Ephesians 5:23] is the seed of Abraham, and therefore of David; but we are not Abraham's seed? We are assuredly; as the Apostle says, "And if you be Christ's, then are you Abraham's seed, and heirs according to the promise." [Galatians 3:29] In this sense, then, let us take the words, brethren, "Your seed will I establish for ever," not only of that Flesh of Christ, born of the Virgin Mary, but also of all of us who believe in Christ, for we are limbs of that Head. This body cannot be deprived of its Head: if the Head is in glory for ever, so are the limbs, so that Christ remains entire for ever. "Your seed will I establish for ever: and set up your throne to generation and generation." We suppose he says, "for ever," because it is "to generation and generation:" since he has said above, with "my mouth will I ever be showing Your truth to generation and generation." What is "to generation and generation"? To every generation: for the word needed not as many repetitions, as the coming and passing away of the several generations. The multiplication of generations is signified and set forth to notice by the repetition. Are possibly two generations to be understood, as you are aware, my beloved brethren, and as I have before explained? For there is now a generation of flesh and blood: there will be a future generation in the resurrection of the dead. Christ is proclaimed here: He will be proclaimed there: here He is proclaimed, that He may be believed in: there, He will be welcomed, that He may be seen. "I will set up Your throne from one generation to another." Christ has now a throne in us, His throne is set up in us: for unless he sat enthroned within us, He would not rule us: but if we were not ruled by Him, we should be thrown down by ourselves. He therefore sits within us, reigning over us: He sits also in another generation, which will come from the resurrection of the dead. Christ will reign for ever over His Saints. God has promised this; He has said it: if this is not enough, God has sworn it. As then the promise is certain, not on account of our deservings, but of His pity, no one ought to be afraid in proclaiming that which he cannot doubt of. Let that strength then inspire our hearts, whence Æthan received his name, "strong in heart:" let us preach the truth of God, the utterance of God, His promises, His oath; and let us, strengthened on every side by these means, glorify God, and by bearing Him along with us, become Heavens.