Stuart reminds us that although the title of "son of God" is used collectively and generically of those to whom it is applicable, it is only used in the singular form of Jesus Christ Himself. Stuart actually rejects the application of the title "Son" To Christ as merely one of moral resemblance. Instead, he only sees two usages of the word "Son" as relevant to the question:
1) Derivation from the Father
2) Kingly office of Messiah
With respect to derivation, Stuart sees the language as purely derivational. That is, it refers to Christ's reception of His human nature upon His incarnation. He compares the usage of the language to the analogy of Adam being the Son of God, and of humans being denominated "sons of God" by an analogy to human birth (cf. Jhn. 1:12-13). Stuart therefore notes that those who accept incarnational sonship to have ground for supposing that this language is applicable to derivation.
Yet Stuart believes that the most important sense in which Christ is spoken of as the Son of God has to do with His being anointed the Messiah and Davidic King. Granted, the Bible does sometimes speak in terms of "sonship" of of creational birth insofar as by means of the incarnation Christ received His human nature by a divine impregnation of Mary. Stuart mentions Lk. 1:35, which we have already noted in previous texts. The Greek word "dio" means "therefore", and so it is clear that the reason for Christ being spoken of as the Son of God is that creational birth by the Holy Spirit. Luke not only refers to Jesus as the Son of God by derivation because of His human nature, but speaks of Adam as the Son of God because of the latter's immediate and direct derivation from God. In each case, "Son" is used with reference to creation:
""The holy child" is called the Son of God, because the "power of the most High" is supernaturally exercised to produce his conception. A common principle led to the appellation, in both cases; viz, the principle that God was, by his power or ifnfluence, in an immediate and supernatural sense, the author or father of both Adam and the "Holy Child""(Stuart).
Stuart makes a crucial point: If the reason Christ is called the "Son of God" is because of His sonship, how could an antecedent sonship have obtained? In that case, this antecedent sonship would itself be the "reason" why Christ is called the Son of God. Indeed, while John's prologue does speak of the eternal preexistence of the Logos, it says nothing about Christ being the "son" of God until it begins to speak of His incarnation (v. 14). "It is then that he speaks of the glory of the only begotten"(Stuart). Therefore, the oft-disputed meaning of the word "monogenes" becomes quite secondary. For if we admit for the sake of the argument that the significance of the word is primarily, or even entirely, one of generation, it can nonetheless be argued with superior plausibility that the generation in John's mind is that of the incarnation (Jhn. 1:14, cf. Lk. 1:35).
Stuart notes Paul's point in Philippians 2, that it is precisely as a consequence of His incarnation, and His obedience in the sufferings and death of this incarnation, that He is given "a name above every name.":
"As God or divine Logos, surely he was not capable of exaltation; but as Messiah, triumphant over death and hell, as the incarnate Saviour, he could be exalted from his state of humiliation and suffering to one of supreme dignity and glory(Stuart).
Apart from His incarnation, another reason Christ is referred to as the Son of God is His Davidic kingship as Messiah. Paul cites Ps. 2:9 in connection with Christ's ascension to Davidic kingship.
"And we bring you the good news that what God promised to the fathers, 33 this he has fulfilled to us their children by raising Jesus, as also it is written in the second Psalm,
“‘You are my Son,
today I have begotten you"(Acts 13:32, 33).
The present writer believes that the language of begottenness refers to His appointment to the position of king, though Stuart offers another reason:
"The resurrection of Christ from the dead, then, is the accomplishment of that prediction in the second Psalm, which speaks of Christ as Son, and of his generation. But why should the resurrection of Jesus constitute a reason for the appellation in question? Others have been raised from the dead besides Jesus. The answer, as it seems to me, must be, that the resurrection of Jesus was the commencement of his elevation to supreme dignity - a pledge, an earnest of all which was to follow. It is thus that the same Apostle seems to view the esubject, in Romans 1:4 "Constituted the powerful Son of God - by his resurrection from the dead...The proper meaning of "orizo" is to limit, define, determine, decree; and secondarily to constitute, because many things are constituted by determining or decreeing. Thus, in Acts 10:42, Christ is said by Peter to "be constituted by God the juge of the living and the dead." And thus in other cases, as may be seen in Schleusner."
Stuart likewise notes thte strangeness of using the verb in the sense of "declared" or "demonstrated":
"It is sufficient to remark here, in justification of the translation which I have given, that with the exception of the case in question, no instance can be produced, in which the word has the sense assigned to it in our Version. It always has respect to something, which is prospective at the time when the action indicated by [the verb] took place, not to any thing in retrospective. Storr, many years since, made this remark upon the force of the word...a remark like most others which he has made on the subject of philology, proceeding from a nice discrimination of the force of the language"(Stuart).
Indeed, the verb used is the same as that translated "predestine", although the original Greek has the prefix indicating temporal antecedence. This is a great example of how the force of the word is clearly prospective rather than retrospective. We were "predestined" to salvation prospectively.
Stuart concedes that Rom. 1:4 may have respect to Christ as Messiah. Stuart then argues that Acts 13:32, 33, "indicates that the resurrection was the commencement of t hat elevation to which Christ was raised; and being a part of his elevation was therefore a reason, why he is called the Son of God"(Stuart).
Stuart also suggests that the force of "Son of God" may to some degree have particular reference, with respect to His resurrection, to the new life given him upon the resurrection, insofar as the contrast between being in a tomb and being raised from is described analogically as a kind of "birth."
"From the moment the new life or resurrection commenced, his elevation began. All in future was to be exaltation. By the resurrection, therefore, he was Son of God on account of a reproduction or reanimantion; as well as constituted Son by being placed in the exalted state of Messiah, or made head over all things to the Church"(Stuart).
Stuart then argues that the significance of "Son of God" to His Christ-hood is also significant. It is by virtue of His kingship that He is denominated "Son of god." This is clear from Matt. 16:15, 16, where Christ asks His disciples who they think He is, and Peter responds "You are the Christ, the Son of the living God." He notes the Markan parallel in Mk. 8:29, and notes that the term "Son of God" is absent. He concludes that it would be strange for the term to be omitted from Mark, did it convey a totally different significance than "Christ." The two, therefore, are synonymous. Indeed, he notes that Lk. 9:20 is different from either, and combines the two, referring to Jesus as "the Christ of God." This indicates with greater strength that the two terms are interchangeable in their significance, and so interchangeable, that they can be combined without confusion of meaning. So also in the Gospel of John:
"But if we doubt that Son of God is here equivalent to Messiah or King of Israel, those doubts may be removed by further examination of the Jewish usus loquendi. "Rabbi," said the Israelite without guile, to his divine Master, "thou art the Son of God, thou art the King of Israel." John 1:49. As in the case above, Son of God ie xplicative of Christ; so here, King of Israel is explicative of Son of God; and if so, then the two phrases are substantially equivalent to each other.
On another occasion, when some who had professed to be the disciples of Jesus had left him, he said to the twelve apostles," Will ye also go away? Then Simon Peter answered him, Lord, to whom shall we go? Thou hast the words of eternal life. And we believe and are sure, t hat thou art the Christ, the Son of the living God." John 6:68, 69. The two expressions here are the same, as in the case of Peter's confession already produced. I cannot but feel that hey constitute a parallelism, in the view of the apostle who uttered them; just as when Thomas said, My Lord and My God, he meant substantially the same thing by both phrases.
In like manner, w hen Jesus asked Martha whether she believed in his power to save from death those who trusted in him, she replied, "Yea, Lord; I believe that thou art the Christ, the Son of God, which should come into the world;" i.e., thou art the Messiah, the expected deliverer and the king of the Jews. John 11:27.
The woman of samaria uses another expression, as parallel to, or exegetical of, the word Messiah or christ. "We know this is indeed the Chrirst, the Saviour of the world." John 4:42"(Stuart).
So an important element of the meaning of terms such as "Christ", "Son of God", and "King of Israel", has to do with the Jewish idiom by which the Jews referred to the Davidic King or Christ. Indeed, it is precisely because the Christ would come from the seed of David that He would be eligible to assume the seat of Davidic King. He argues much the same concerning the Sanhedrin's interrogation of Jesus in Lk. 22:67, 70 and Matt. 26:63. When He is asked whethe ror not He is the Christ, they annex to this title the explicative "Son of God": "I adjure you by the living God that you tell us, whether you are the Christ, the Son of God." For Christ to be the Son of God, therefore, has nothing whatsoever to do with Him being eternally generated of the Father. Such a reading is obviously absurd. The Jews had no concept of any such thing. For them, to be the Son of God had reference to occupying the seat of the Davidic throne by virtue of the Messiah's descent from Him:
"Enough had been adduced to shew the usus loquendi of the apostolic age, among the Jews. Let it now be called to mind, that every writer or speaker, who means to be understood, must necessarily use language in the same sense, in which the age and nation to which he belongs use it. And if this be admitted, how shall we avoid the conclusion, that Son of God was the designation of Christ as the expected Messiah of the Jews, as the King who was to subdue all nations, and reduce them under his government?"(Stuart).
Stuart argues that Ps. 2:7 is a prophecy of something that would occur in the future, and not an eternally true reference to Christ as the eternally generated or eternally begotten Son.
"Yet have I set my King upon my holy hill of Zion. I will publish the decree." What decree? Why plainly that which makes or constitutes him King. And what is it? "The Lord hath said to me, Thou art my Son; this day have I begotten thee." This is the decree or sentence, which constitutes him King in zion. What follows this elevation? Why, that all nations shall come under his dominion, and that his enemies shall be dashed in pieces.
Surely no other generation of the Son is intimated here, but his exaltation to the dignity of King and Lord. And it is in exact consonance with this, that Peter explains the very passage in question, in Acts 13; accommodating it to the resurrection of Christ, which was the very circumstance that commenced his elevation to the throne of supreme dominion"(Stuart).
In light of this, it is difficult to imagine on what grounds those who believe in eternal generation believe that Psalm 2:7-9 has reference to Christ's eternal begottenness. Stuart points out how nonsensical it would be to suppose that the text would have prophesied the future occurrence of something which had always been true. Obviously the text has reference to a future occurrence which has yet to commence. Stuart notes from other texts the proleptic and prophetic nature of the text, such as 2 Sam. 7:14, which refers to a future time during which God would be to the King of Israel a Father, and He to God, a Son. Likewise, Ps. 89:3, 4, 20-27: "He shall cry to me, Thou art my Father - And I will make him my firstborn."
"Here we have predictions, not only of a future Son, but of a future first born. I am unable to conceive, how that which existed from all eternity, should be thus spoken of as yet to exist, at a future period. If I am correct then, the Logos, before his incarnation, was not, strictly speaking, Son of God, but only to become so by union with the person of Jesus [since this Davidic Kingship was Jesus' inheritance by virtue of His genealogy]. And is it not thus, that the apostle John represents the subject, when he introduces the Logos to our consideration, as he existed in a previous state?...it was only after "he became flesh and dwelt among us, that the apostle speaks of "the glory of the only Begotten, full of grace and truth", which the disciples saw. It is the "only begotten Son, who is in the bosom of the Father, (i.e. most dear to him or beloved by him,) that hath declared him." Surely it is the Messiah, and he only who has made such a revelation; not the Logos before the incarnation"(Stuart).
Stuart, Moses. "Letters on the Eternal Generation of the Son." Andover. 1822.