The Son's subjection is for our sake, as head of his members

So when he says “Sit,” that marks a beginning, and when he says “until your enemies are made a footstool for your feet,” that shows an end. But when all things are subjected to him, then the Son himself will also be subjected to the one who subjected all things to him, so that God may be all in all (1 Corinthians 15:28). This is what it means: when we all are subjected to the Son, we are found to be his members, and we become sons of God in him. “For you,” he says, “are one in Christ Jesus” (Galatians 3:28). Then he himself will be subjected to the Father on our behalf, as head for his own members. For as long as all his members have not yet been subjected, he, their head, has not yet been subjected to the Father, but is awaiting his own members. If he were one of those who are subjected, he would have been subjected to the Father from the beginning, and would not be doing this at the end. For we are the ones who are subjected to the Father in him, and we are the ones who reign in him, until our enemies are placed under our feet. For because of our enemies the Master of the heavens came in our likeness, and took the human throne of David, his father according to the flesh, in order to rebuild it and set it upright. So that when it is set upright, we all might reign in him, and he might hand over the human kingdom, set upright, to the Father, so that God may be all in all, reigning through him as through the Word of God, after he has reigned through him as through a human savior. And when Peter says, “Let all the house of Israel therefore know for certain that God has made this Jesus, whom you crucified, both Lord and Christ” (Acts 2:36), he is not speaking about his divinity when he says that God made him Lord and Christ, but about his humanity, which is the whole Church, which reigns and rules in him after he was crucified, and is anointed for the kingdom of heaven, so that it may reign with him, who emptied himself for her sake and took her up through the form of a servant. For the Word and Son of God was always Lord and God, and did not become Lord and Christ after being crucified. Rather, as I said before, his divinity made his humanity Lord and Christ. And when he says, “Father, if it is possible, let this cup pass from me; yet not my will but yours be done” (Matthew 26:39), and “The spirit is willing, but the flesh is weak” (Matthew 26:41), he shows two wills here: one human, which belongs to the flesh, and one divine, which belongs to God. For the human will, because of the weakness of the flesh, declines the suffering; but his divine will is ready. And just as Peter, when he heard about the suffering, was afraid and said, “Far be it from you, Lord!” and the Lord rebuked him, saying, “Get behind me, Satan! You are a stumbling block to me, because you are not thinking the things of God but the things of men” (Matthew 16:22-23), so it is understood here as well. For having come in the likeness of men, he declines the suffering as a man; but being God, and being without suffering according to his divine substance, he willingly accepted the suffering and death, because it was not possible for him to be held by death. For he was God, having come in the likeness of men, dying willingly and rising by his own authority as God, as David also said: “Let God arise, and let his enemies be scattered” (Psalm 68:1), and again: “Awake, Lord my God, in the command which you commanded, and a congregation of peoples will surround you” (Psalm 7:6-7).