Psalms 2:7

7.I will declare, etc. David, to take away all pretense of ignorance from his enemies, assumes the office of a preacher in order to publish the decree of God; or at least he protests that he did not come to the throne without a sure and clear proof of his calling; as if he had said, I did not, without consideration, publicly go forward to usurp the kingdom, but I brought with me the command of God, without which, I would have acted presumptuously, in advancing myself to such fin honorable station. But this was more truly fulfilled in Christ, and doubtless, David, under the influence of the spirit of prophecy, had a special reference to him. For in this way all the ungodly are rendered inexcusable, because Christ proved himself to have been endued with lawful power from God, not only by his miracles, but by the preaching of the gospel. In fact, the very same testimony resounds through the whole world. The apostles first, and after them pastors and teachers, bore testimony that Christ was made King by God the Father; but since they acted as ambassadors in Christ’s stead, He rightly and properly claims to himself alone whatever was done by them. Accordingly, Paul (Ephesians 2:17) ascribes to Christ what the ministers of the gospel did in his name. “He came,” says he, “and preached peace to them that were afar off, and to them that were nigh.” Hereby, also, the authority of the gospel is better established because, although it is published by others, it does not cease to be the gospel of Christ. As often therefore, as we hear the gospel preached by men, we ought to consider that it is not so much they who speak, as Christ who speaks by them. And this is a singular advantage, that Christ lovingly allures us to himself by his own voice, that we may not by any means doubt of the majesty of his kingdom.

On this account, we ought the more carefully to beware of wickedly refusing the edict which he publishes, Thou art my Son. David, indeed could with propriety be called the son of God on account of his royal dignity, just as we know that princes, because they are elevated above others, are called both gods and the sons of God. But here God, by the singularly high title with which he honors David, exalts him not only above all mortal men, but even above the angels. This the apostle (Hebrews 1:5) wisely and diligently considers when he tells us this language was never used with respect to any of the angels. David, individually considered, was inferior to the angels, but in so far as he represented the person of Christ, he is with very good reason preferred far above them. By the Son of God in this place we are therefore not to understand one son among many, but his only begotten Son, that he alone should have the pre-eminence both in heaven and on earth. When God says, I have begotten thee, it ought to be understood as referring to men’s understanding or knowledge of it; for David was begotten by God when the choice of him to be king was clearly manifested. The words this day, therefore, denote the time of this manifestation; for as soon as it became known that he was made king by divine appointment, he came forth as one who had been lately begotten of God, since so great an honor could not belong to a private person. The same explanation is to be given of the words as applied to Christ. He is not said to be begotten in any other sense than as the Father bore testimony to him as being his own Son. This passage, I am aware, has been explained by many as referring to the eternal generation of Christ; and from the words this day, they have reasoned ingeniously as if they denoted an eternal act without any relation to time. But Paul, who is a more faithful and a better qualified interpreter of this prophecy, in Acts 13:33, calls our attention to the manifestation of the heavenly glory of Christ of which I have spoken. This expression, to be begotten, does not therefore imply that he then began to be the Son of God, but that his being so was then made manifest to the world. Finally, this begetting ought not to be understood of the mutual love which exists between the Father and the Son; it only signifies that He who had been hidden from the beginning in the sacred bosom of the Father, and who afterwards had been obscurely shadowed forth under the law, was known to be the Son of God from the time when he came forth with authentic and evident marks of Sonship, according to what is said in John 1:14, “we have seen his glory, as of the only begotten of the Father.” We must, at the same time, however, bear in mind what Paul teaches, (Romans 1:4) that he was declared to be the Son of God with power when he rose again from the dead, and therefore what is here said has a principal allusion to the day of his resurrection. But to whatever particular time the allusion may be, the Holy Spirit here points out the solemn and proper time of his manifestation, just as he does afterwards in these words

“This is the day which the Lord hath made;
we will rejoice and be glad in it.” (Psalms 118:24)