In his section on the Trinity in The Doctrine of God,1 Frame gives four lines of explanation for texts that teach that the Son is in some sense less than or subject to the Father. He is commenting specifically on John 14:28; and 1 Corinthians 11:3; and 15:28.
In his first comment, Frame offers what strikes me as a potentially helpful perspective on the issue of the eternal subordination of the Son to the Father. Complementarians and egalitarians agree that during the incarnation the Son was functionally subordinate to the Father. Where they disagree is (1) how long that subordination lasts and (2) on what basis it exists. Frame thinks it lasts eternally on the basis of His eternal humanity.
1. Jesus utters these words in what the Westminster Catechisms call his “state of humiliation” (WLC, 42–57; WSC, 23–28). In John 14, he faces the cross itself. But throughout his earthly ministry, he lives in subjection to his Father, As prefect, man he obeys, God, seeks God’s blessing in prayer, and does the works the Father show shim. He cannot act by himself, but only in subjection to the Father (John 5:30). He treats the Father, in other words, as any covenant servant should: as his superior, as the one who is greater. And, as Jesus remains both human and divine through all eternity, he will, as human servant, always be subject to the Father in these ways.
. . .
The case is similar in regard to 1 Corinthians 11:3 (“the head of Christ is God”) and 15:28 (“then the Son himself will be made subject to him who put everything under him, so that God may be all in all”), where I think the first consideration above is determinative. As the servant of God, who remains eternally man as well as God, Jesus demonstrates his obedience by subjecting himself to the headship of God the Father. (682–83, emphasis added)
If Frame is correct, then the eternal subordination of the Son is linked to the eternal humanity of the Son. The Son will always be in some sense subject to the Father since (1) He is a man (2) and no man—even glorified man—can be equal with God. It seems quite likely, then, that the Son is and will eternally be subordinate to the Father with respect to His humanity.
But this raises at least one question in my mind: how do we account for what seems to be a change of state from not subordinate to subordinate: ὅταν δὲ ὑποταγῇ αὐτῷ τὰ πάντα, τότε [καὶ] αὐτὸς ὁ υἱὸς ὑποταγήσεται τῷ ὑποτάξαντι αὐτῷ τὰ πάντα? The implication is that immediately prior to that point the Son is not subject to the Father (at least not in the sense that He is about to be subjected to Him). If the subordination of the Son is linked to His humanity, how is it that that subordination seems to have a temporary break during His reign?
It seems that the sense in which the Son will be subordinated (according to 1 Cor 15:28) is the same as the sense in which He is presently not subordinated. If that is the case, I cannot see how that sense is as Frame suggests Christ’s humanity (for obviously Christ remains human during His reign and would thus be subordinate in that sense during His reign). I think Frame is likely correct in his assertion that the Son is subject to the Father with regard to His humanity, but for now I’m inclined to think that this is not the subjection that 1 Corinthians 15:28 addresses.
What that subjection is I’m still trying to discern.
Thoughts? What am I missing? What assumptions am I making that need to be questioned?