I have argued that the original Christological formula quoted by Paul went as follows:
“born of the seed of David, according to the flesh;
marked out Son of God, according to the Spirit of holiness”
The point of the primitive formula was to explain the identity of Jesus in terms of his two natures, human and divine, using two of his most important titles as keywords: “seed of David” and “Son of God.”
In focusing on the two natures of Christ, my view is similar to the Hodge-Warfield view. Yet it is slightly different in that I do not take “the Spirit of holiness” as denoting the divine nature of Christ but rather the Holy Spirit. The divine nature of Christ is denoted by the term “Son of God.”
In keeping with this, I argued that the verb horizo is to be translated “marked out,” since it would not make sense to say that he was “appointed” the divine Son of God. Rather, he was marked out as such by the Spirit’s powerful activity in his earthly ministry.
Now, perhaps you may be questioning the validity of taking “Son of God” in an ontological/divine sense rather than a functional/messianic sense. After all, the Davidic king was a “son of God” in some sense without making him divine (2 Sam 7:14; Ps 2:7). This is a widely-held interpretation of the title “Son of God.”
For example, Schreiner argues that
“The appointment of Jesus being described here [in Rom 1:3-4] is his appointment as the messianic king … The title huiou theou in verse 3 is a reference not to Jesus’ deity but to his messianic kingship as the descendant of David.”
[Thomas Schreiner, Romans (BECNT; Grand Rapids: Baker, 1998), 42].
I’m not accusing Schreiner of heresy but he has bought into this notion of a functional “messianic sonship” (at least in this text - I’m sure he would acknowledge higher meanings elsewhere). But this category, as applied to Jesus, just does not exist in the NT. I would challenge anyone to look up all 131 references to Jesus as “Son,” “the Son,” “Son of God,” “Son of the Most High God,” “My Son,” etc., in the NT. If you do that, you will see that the title “Son of God” – when applied to Jesus in the NT – is primarily about ontological not functional status. It has to do with his status as the eternal, divine Son. This is not only true in the Pauline epistles (17x), the Gospel of John (27x), the Johannine epistles (24x), and Hebrews (12x), where we might expect such divine nuances. It is also true in the Synoptic Gospels, including the most primitive layers of the tradition – Matthew (22x), Mark (11x), Luke (14x).
An excellent discussion of the meaning of the title “Son of God” in the Gospels can be found in chapter 12 of George Eldon Ladd’s Theology of the New Testament. Ladd argues that the two titles, “Son of God” and “Messiah,” are not equivalent in the Gospels.
For example, at the beginning of his public ministry, immediately after being baptized by John, the voice from heaven declares: “You are my beloved Son; with you I am well pleased” (Mk. 1:11). In what sense is Jesus here designated God’s Son? It is tempting to think that at his baptism, Jesus became God’s Son in the messianic sense, that is, he was appointed to messianic sonship in the sense of Psalm 2:7.
But Ladd argues that the while Psalm 2:7 is alluded to, it is only quoted partially. “I have begotten you” is left out. Instead, a clause from Isaiah 42:1, “with whom I am well pleased,” is added. Ladd argues that this clause should be translated, “whom I have chosen” (cp. LXX). Ladd writes:
“The heavenly voice may therefore be rendered, ‘This is my only Son; him I have chosen.’ Sonship and messianic status are not synonymous. Rather, sonship is the prior ground and the basis of Jesus’ election to fulfill his messianic office … He does not become the Son; he is the Son. Sonship is antecedent to messiahship” (163-4).
[George Eldon Ladd, A Theology of the New Testament (rev. by Donald A. Hagner; Grand Rapids: Eerdmans, 1993.]
He is the eternal Son of God. The eternal Son is chosen to be the Messiah. At his baptism, the voice from heaven proclaims that the eternal Son of God is now appointed Messiah.
This is reinforced by Jesus himself in the following pericope found in all three Synoptic Gospels:
Now while the Pharisees were gathered together, Jesus asked them a question, saying, “What do you think about the Christ? Whose son is he?” They said to him, “The son of David.” He said to them, “How is it then that David, in the Spirit, calls him Lord, saying, ‘“The Lord said to my Lord, sit at my right hand, until I put your enemies under your feet’? If then David calls him Lord, how is he his son?” (Matt 22:41-45 ESV).
Yes, Jesus is the son of David, the anointed King, the Messiah. But he is much more than that. He is not only David’s son; he is also David’s Lord who as deity is worthy to sit at the right hand of God. Whose son is he? He is David’s son (as to his human nature) and he is God’s Son (as to his divine nature). The Jews expected a purely human messiah, a political deliverer, but not a divine Savior who would die as a ransom for sinners and be raised and exalted to the right hand of God to be the object of faith and worship.
Let’s return to the primitive formula. That formula, I argue, was used by the earliest Jewish Christian community as a handy way of summarizing who Jesus is. Just as the baptism of Jesus distinguishes the two aspects of Jesus’ identity – eternal Son of God, then appointed Messiah – so the Christological formula quoted by Paul in Rom 1:3-4 explains the identity of Jesus in terms of his two sonships, but in reverse order: “seed of David” (or Messiah) as to his human nature, but much more than that – he was also marked out the divine “Son of God,” as evidenced by the powerful operation of the Spirit given to the Son “without measure” (which operation of the Spirit, Paul adds, was powerfully demonstrated at his resurrection).