Answer: In both statements there seems no small confusion through inattention to scripture.
1. The Father and the Son, as such, do not appear in Psa. 110. It is wise to adhere to scripture. The true correlates here are Jehovah and Messiah. No doubt the persons may be otherwise and elsewhere so regarded; but beyond controversy what the Psalm reveals is Jehovah saying to David’s Lord, the Messiah, Sit Thou at My right hand until I make Thine enemies Thy footstool. Nor in fact does scripture ever, that I remember, speak of the right hand of the Father, but of God, and avoids it pointedly as in Acts 2:3333Therefore being by the right hand of God exalted, and having received of the Father the promise of the Holy Ghost, he hath shed forth this, which ye now see and hear. (Acts 2:33). Surely also the N. T. which speaks of “evangelistic work” connects it with the Son yet more than the Father. It was He, not the Father, Who came to seek and to save the lost. It is not said of “the Father,” but that “God so loved the world that He gave” &c. The truth is that in the O. T. Jehovah and His Anointed have perfect communion in “outward judgments,” as in the N. T. Father and Son have in “evangelistic work.” The Law, Psalms, and Prophets prove the former, as the Gospels and Epistles the latter, the Revelation bringing us round transitionally to the world-kingdom of the Lord and His Christ, and the eternal state which follows again confirming their fellowship in judgment as before in grace.
Nor can any interpretation be more egregious than that Jehovah’s making Messiah’s enemies to be Messiah’s footstool means “converting grace.” Subjecting them to Christ it is, but this, as 1 Cor. 15 slums, for actively putting down and annulling all antagonistic power. Such is one of the main objects of “the kingdom,” which is as distinct from the gospel and the church as from eternity.