In his commentary on Romans, the Scottish theologian Robert Haldane (1764-1842), attempted to unpack what the sonship of the Son entailed. Commenting on the third verse of the first chapter, Haldane wrote:
The gospel of God concerns his Son. The whole of it is comprised in the knowledge of Jesus Christ; so that whoever departs one step from him departs from the gospel. For as Jesus Christ is the Divine image of the Father, he is set before us as the real object of our faith.
Exposition of the Epistle to the Romans, 19.
So the sonship of the Son relates to his image-bearing of the invisible God (Col 1:15). His sonship is unique in this way, even if it has been revealed to us in the relational language of Father and Son.
Intelligible, but Unique
The qualities of paternity and filiation, are technical descriptions of the Father and the Son, respectively. As high as these unique descriptions are, they still tell us something intelligible. The persons of the Trinity are not called God 1, 2 and 3, but Father, Son and Holy Spirit. The Son’s uniqueness doesn’t mean his sonship is unintelligible. But in our limited comprehension, we must be humble and accept that he is a Son like no other.
On the basis of the uniqueness of the Son in all respects, Haldane argues that he has the same nature as the Father, and differentiates the Son from all other types of sons. He wrote:
“He is the Son of God, his own Son, the only begotten of the Father; which proves, that he is truly and exclusively his Son, of the same nature, and equal with the Father, and not figuratively, or in a secondary sense, as angels or men, as Israel or believers”
Ibid, 20.
Haldane believed that the Son shared the same essence as the Father because he is the only begotten of the Father. So an unpartitioned divine nature was the Son’s. He is equal with Father, which his Sonship proves.
Chalcedonian logic
Rather than viewing the description of “Son” as a lesser title than Father, Haldane noted what the orthodox have always known, that the Sonship of the Son, speaks to his shared, co-equal, divine essence. The Son, is “consubstantial [co-essential] with the Father according to the Godhead”, according to the creed of Chalcedon. Yet with this divine nature is added his human nature. As the Chalcedonian creed summarized the relationship:
one and the same Christ, Son, Lord, only begotten, to be acknowledged in two natures, inconfusedly, unchangeably, indivisibly, inseparably; the distinction of natures being by no means taken away by the union, but rather the property of each nature being preserved, and concurring in one Person and one Subsistence, not parted or divided into two persons, but one and the same Son, and only begotten, God the Word, the Lord Jesus Christ
Fourth Ecumenical Council, Chalcedon, 451AD.
This Chalcedonian way of speaking was certainly what Haldane confessed. And following Paul, Haldane understood the significance of the title, “Son of God”:
That the Lord Jesus Christ, in his eternal equality with the Father and not merely as God manifested in the flesh, is called the Son of God, flows directly from the fact, that wherever the first person of the adorable Trinity is personally distinguished in Scripture, it is under the title, the co-relative title of the Father.
Ibid, 20.
In the early nineteenth century, it was necessary for Haldane to make these points. He needed to affirm that the Sonship of the Son vindicated his deity.
Haldane’s Caution
Following a century of rationalism, Haldane constantly re-affirmed a high and historic view of the divine Trinity. He cautioned against the temptation to speculate when discussing the doctrine of God. The easiest temptation which Christian’s face is to suppose that the Sonship of the Son is somehow a lesser ‘derivation’. Haldane dealt with this objection saying:
And what is the objection to this doctrine of our Lord’s eternal Sonship? It is simply, that it differs from all our ordinary notions of the filial relation to represent the Son as co-eternal with the Father; or that begotten must necessarily mean “derived,” and that to grant derivation is to surrender Deity.
Exposition, 20.
Haldane wanted to hedge against the temptation to restrain the Sonship of the Son to our human ideas of sonship alone. This ‘derived personality’ was a way for the rationalists to deny the deity of the Son but affirming the language of sonship.
Haldane expressed the objections to sound doctrine and the wrong thinking from which it came from:
To demand that the distinction of persons in the undivided essence of the Godhead, and the mode of their eternal substance shall be made plain to us; or to repugn against the doctrine of the eternal filiation of the Son of God, because it overpasses the boundaries of our notions of Sonship, what is this but the very summit of unthinking arrogance?
Ibid, 20.
As we consider the Sonship of the Son, we need to be careful about our tendencies to be elevated to a “summit of unthinking arrogance”. At the same time, like Haldane, we need to look at Scripture and explore the significance of the ways that God has described himself, all of the predicates and titles.