Which he promised before through his prophets in the Holy Scriptures concerning his Son. Here the parenthetical passage begins, extending to the end of Romans 1:6. It is unnecessary to complicate it by connecting περὶ τοῦ υἱοῦ αὐτοῦ with the previous εὐαγγέλιον θεοῦ. It goes more naturally with προεπηγγείλατο, denoting the subject of the Old Testament promises. By προφητῶν are meant not only the sacred writers distinctively so called, but (as in Hebrews 1:1) all who spoke of old under Divine inspiration, as by γραφαῖς ἁγίαις is signified the Old Testament generally. This intimation of the gospel being the fulfilment of prophecy is fitly introduced here, as preparing the reader for the argument of the Epistle, in the course of which the doctrine propounded is shown to be in accordance with the Old Testament, and in fact anticipated therein. This is, indeed, a prominent point in the general teaching of apostles and evangelists. They announce the gospel as the fulfilment of prophecy, and the true completion of all the ancient dispensation; and it is to the Old Testament that, in addressing Israelites, they ever in the first place appeal. Thus St. Peter (Acts 2:14; Acts 3:18; Acts 4:11); thus Stephen (Acts 7:1-60.); thus St. Paul at Antioch in Pisidia, at Thessalonica, and before Agrippa (Acts 13:16; Acts 17:2; Acts 26:6, Acts 26:22); thus Philip to the Ethiopian proselyte (Acts 8:35); thus Apollos at Corinth (Acts 18:28). Our Lord himself had done the same, as in Matthew 5:17; Luke 4:21; Luke 24:27, Luke 24:44; John 5:39. All this is important as showing how the old and new dispensations are regarded together as parts of a whole, the old one being but the needful preparation for a fulfilment in the new, and so becoming intelligible; and thus how "through all the ages one eternal purpose runs." There was also a providential preparation in the Gentile world, though not so direct and obvious, and though, of course, not similarly noticed in addresses to disciples of the Law. But St. Paul intimates it; as in his speech on Areopagus, and also, as will be seen, in this Epistle. Even the gospel is set forth as but a further stage of progress towards a final consummation, as the dawn only of a coming daybreak. We have still but an earnest of our inheritance; the "earnest expectation of the creature" still awaits "the manifestation of the sons of God." Meanwhile, in the revelation already made through Christ, and the redemption accomplished by him, we are taught to cling to our faith in a Divine purpose throughout the world's perplexing history—that of resolving at last all discords into eternal harmony, and making manifest "one great love, embracing all." This grand view of a providential order leading to a final consummation (though how and when we know not) pervades St. Paul's writings, and should be kept in mind for a proper understanding of this Epistle. God's promises through his prophets in Holy Scripture are said to have been "concerning his Son;" and a question hence arises as to the exact sense in which "his Son" is to be here understood; a consideration of which question may help our interpretation of the expression in the following verse, which is not without difficulty, τοῦ ὁρισθέντος υἱοῦ θεοῦ ἐν δυνάμει. We may distinguish between three senses in which Christ is called "the Son of God."
In all these passages—except (3), in which the reference may be only to Christ in glory—the term "Son" denotes a relation (o the Father, peculiar to our Lord, previous to the death and exaltation, and in some of them, (2), (6), (7), previous to the Incarnation. Such previous relation is especially apparent in the sequence to (7), where "the Son of his love" is defined not only as "the Head of the body, the Church," and "the Firstborn from the dead," but also as "the Image of the invisible God, the Firstborn of all creation; for in him all things were created, the things in heaven, and the things on the earth, the things visible and the things invisible; all things through him and unto him have been created." With this may be compared Philippians 2:6-12, where an existence ἐν μορφῇ θεοῦ, anterior to incarnation, is undoubtedly declared, though the exaltation after human obedience, and the receiving then of "a name that is above every name" (cf. Hebrews 1:4), is spoken of as well. One other passage remains to be noticed, occurring, not in an Epistle, but in the sermon at Antioch in Pisidia (Acts 13:33), where the view of Christ's Sonship which is found in the Epistle to the Hebrews (no more being expressed) appears as present to St. Paul's mind. For there God is said to have "fulfilled the promise which was made unto the fathers, in that he hath raised up Jesus again; as it is also written in the psalm, Thou art my Son; this day have I begotten thee." Here the Sonship assigned to "the Christ" in the second psalm is regarded as exhibited in the Resurrection. From this review of St. Paul's usage it may be inferred that περὶ τοῦ υἱοῦ αὐτοῦ in the text before us carries with it in his own mind the idea of pre-existent eternal Sonship, though what we may call Messianic Sonship may be all he means distinctly to intimate as declared by prophets. The bearing of this distinction on the interpretation of Philippians 2:4 will appear under it. It may be observed here that the absence of a fixed and definite usage in the application of the term "Son" to Christ, which (as has been seen) is found in the New Testament, is what might be expected there. Formal definitions of theological conceptions by means of language used uniformly in a recognized definite sense had not as yet been made. Among such conceptions that of the Holy Trinity though implied, is nowhere distinctly formulated as a dogma. It was reserved for the Church, under the guidance of the Spirit, to preclude misconception by precise dogmatic definitions.