number of reasons, scholars generally believe that Paul is alluding to earlier
Christian tradition in Romans 1:3-4. One reason for thinking Paul is citing
earlier tradition is the odd vocabulary and turns of phrase he uses that he
uses nowhere else even when he is saying similar things:
1. Except for 2 Timothy (which rightly or wrongly most argue to be pseudonymous), Paul nowhere else refers to Jesus as the Son of David.
2. This use of flesh is not his most usual--more often than not he speaks of flesh as the foothold of sin in a person's body, especially when it is in contrast to spirit.
3. He nowhere else uses "appointed" or "Son of God in power" in this way, although he makes analogous comments elsewhere in relation to Jesus getting the title "Lord."
4. "Spirit of holiness" is completely unique to this passage, as he simply says "Holy Spirit" elsewhere. This seems to be a Hebraism found in the Hebrew of Isaiah and certain Psalms.
When you add to some of these verbal aspects the structure of the statement (relative clauses with parallel affirmations, etc...), it seems more likely than not that Paul is alluding to something he didn't compose but that the original audience knew.
The parallel between body and spirit seems to form the heart of the contrast between verses 3 and 4. Verse 3 presents Jesus according to the flesh; verse 4 presents Jesus in spiritual terms. The parallel is not exact, for the Spirit of holiness is surely a reference to the Holy Spirit rather than Jesus' spirit (and it seems highly anachronistic to see this in some Trinitarian sense since Christians would not start thinking of these issues for at least another hundred years later).
Dunn and perhaps most would see in these verses reflections of a "two stage Christology." The first is the earthly phase: "Son of David." But when Christ rises from the dead, he is enthroned "Son of God in power." The normal use of "appointed" implies that Christ attains a new "state" that he did not have in the "Son of David" phase. However, the qualification "in power" may imply that he was Son of God before--just not Son of God in power.
In NT Survey classes I sometimes point out that the early Jewish Christians got a lot more in a Messiah than they bargained for. They would have been content with a human Messiah who kicked the Romans out of
The appointment/enthronement of Jesus as Son of God in power is attested at several points in the New Testament. Acts 13:33 is a noteable parallel where a sermon considers Christ's exaltation to God's right hand to be the place where God declares Christ "Son." Hebrews similarly at 1:5 locates the designation of Jesus as Son of God to the point of his exaltation. We find also in Acts and Paul indicates that Jesus most meaningfully receives the title "Lord" at his resurrection (e.g., Acts 2:35; Phil. 2 in the hymn;
Some scholars think that the phrase "in power" is a Pauline addition to the pre-existing formula (e.g., Fitzmeyer). Others disagree (e.g., Dunn). I can accept it as original and pre-Pauline because the two statements are not exactly parallel anyway.
Dunn argues that the way the comment "on the basis of the resurrection of the dead" is worded points to a pre-Pauline origin, because it is worded in terms of the general resurrection rather than Christ's specific resurrection. Paul connects Christ's resurrection to the general resurrection of all as well, but by his time they are clearly understood to occur in at least two distinct phases (see 1 Cor.). Originally, Dunn suggests, the first Christians would have seen Christ's resurrection as the immediate or at least very near commencement of the full blown final resurrection of the dead. The pre-Pauline formula would thus embody what we find in Matthew 27 where the resurrection of certain saints of renown occurs in the context of Christ's death--an indication of the beginning of the general resurrection.
But other commentators (e.g., Fitzmeyer) think that this phrase is similarly a Pauline addition to the formula on the basis of Paul's focus on resurrection. If forced to conclude, I would go with Dunn, since the expression does not seem to be Paul's normal way of referring to the resurrection.