According to Reformed theology, where is the Scriptural evidence for homoousion?

Question

The Westminster Confession of Faith says:

The whole counsel of God, concerning all things necessary for his own glory, man’s salvation, faith, and life, is either expressly set down in scripture, or by good and necessary consequence may be deduced from scripture: unto which nothing at any time is to be added, whether by new revelations of the Spirit, or traditions of men.

According to Reformed Theology, where is homoousion either "expressly set down" or "deduced" from the bible?

This question is related, but it only deals with when and how homoousion was used prior to the Nicene Council.

Answer 1

Before we get into the weeds, here are the main points that I intend to impart:

• Reformed theology generally accepts the church fathers' wisdom on the homoousion.

• The concept of homoousion, not the term, is what matters most.

• The concept of homoousion safeguards the Gospel against Arianism.

• There is no single proof-text for the term, but the concept is inseparable from the Biblical witness.

And now we move into the weeds.

Francis Turretin, author of one of the classic reformed systematic theologies, affirmed that the church father Basil was correct to advance the term despite a lack of singular proof-texts:

Francis Turretin [Institutes of Elenctic Theology, 1:37-39] asked whether Christian doctrine was to be legitimately proved "only by the express word of God" or also from "consequences drawn from Scripture." He observed that "a thing may be said to be in Scripture in two ways: either kata lexin (expressly and in so many words); or kata dianoian (implicitly and as to the sense." It is unnecessarily reductionist to suggest that a doctrine is biblical only if a proof text can be adduced. Turretin drew attention to Basil's response to the Arians in which he argued that their demand for a proof text to establish the homoousion rendered them "syllable-catchers."

Mark D. Thompson, "The Divine Investment of Truth," in Do Historical Matters Matter to Faith, 75

The church father Athanasius believed that the concept has its origin in the New Testament:

Athanasius ... rightly recognized that the proper understanding of the homoousion was lodged within the New Testament from the outset. The homoousion may be a word foreign to the New Testament, but it was, ultimately, not a concept foreign to the New Testament, for the New Testament proclamation did not simply give rise to it but actually contained its meaning.

Thomas Weinandy, Athanasius: A Theological Introduction, 136

For Athanasius, the entire Gospel was at stake in the debate against Arianism:

It must be stressed that so far as Athanasius was concerned it was not the word homoousios itself that was of central importance, but what the word stood for. There was no substantial change in his position when he came more and more to use homoousios in his writings: it served simply to focus and concentrate the entire debate with Arianism. What it meant for Athanasius was simply this: that the reality of God himself is present with us and for us in Christ. "One ousia" means "one divinity", "one activity", "one presence", "one glory", "one power and energy": all that the Father is, the Son is also, except that the Father is Father, the Son, Son. This was the decisive difference between Athanasius and Arianism; for any assertion of this kind was, in the Arian horizon, strictly incorrect and untrue. For Arius and his followers, however, the point might be expressed, decorated or qualified, the Son is not God as the Father is God; for Athanasius, he is.

[From Athanasius' perspective,] what was missing in Arius' entire scheme was, quite simply, God himself. True, he was there—after a fashion. He was there, but he was silent, remote in the infinity of his utter transcendence, acting only through the intermediacy of the Son or Word, between whose being and his own, Arius drew such a sharp distinction. The God in whom Arius believed had no direct contact with his creation; he was for ever and by definition insulated and isolated from it in the absolute serenity of an unchanging and unmoving perfection. God himself neither creates nor redeems it; he is involved with it only at second hand. This is on the one hand the corner-stone of Arius' theology, and on the other the point of fundamental contrast with Athanasius. This remote transcendence, Athanasius rightly sees, has nothing to do with the God of the Old and New Testaments, the Father of Christ. When Arius' system is put to question, not simply about its own internal logic, but about its adequacy as a means of interpreting and expressing the Gospel, it is found to be hopelessly inadequate; for the Bible speaks of a God who is present and who does act in and for the world which in his own, and whose presence and activity are uniquely concentrated in the man Jesus who is at the same time Immanuel, God-with-us. For Arius, that cannot really be; for Athanasius, it is the centre around which everything else falls into place.

Alasdair I.C. Heron, "Homoousios with the Father," in The Incarnation, 68-69

Here's an example of Athanasius' scriptural reasoning at work in the homoousion controversy:

The bishops ... were again compelled on their part to collect the sense of the Scriptures, and to re-say and re-write what they had said before, more distinctly still, namely, that the Son is 'one in essence' with the Father: by way of signifying, that the Son was from the Father, and not merely like, but the same in likeness, and of showing that the Son's likeness and unalterableness was different from such copy of the same as is ascribed to us, which we acquire from virtue on the ground of observance of the commandments. For bodies which are like each other may be separated and become at distances from each other, as are human sons relatively to their parents (as it is written concerning Adam and Seth, who was begotten of him that he was like him after his own pattern); but since the generation of the Son from the Father is not according to the nature of men, and not only like, but also inseparable from the essence of the Father, and He and the Father are one, as He has said Himself [John 10:30], and the Word is ever in the Father and the Father in the Word [John 10:38], as the radiance stands towards the light (for this the phrase itself indicates), therefore the Council, as understanding this, suitably wrote 'one in essence,' that they might both defeat the perverseness of the heretics, and show that the Word was other than originated things. ... If the Son is Word, Wisdom, Image of the Father, Radiance, He must in all reason be One in essence.

Athanasius, De Decretis, 20,23

Lastly, observe how reformed theologian Stephen J. Nichols affirms each of the main points listed above while citing additional verses for reference:

The bishops at Nicea concluded that homoousios alone measured up to the standard of biblical teaching. The Nicene Creed declares that Jesus is "very God of very God, begotten not made, being of one substance with the Father." This creed is not uncovering new ground. Rather, it summarizes the massive swath of biblical material regarding the person of Christ. The author of Hebrews begins by declaring, "He is the radiance of the glory of God and the exact imprint of his nature" (Heb. 1:3). Paul says rather directly that in Jesus "dwells the whole fullness of deity bodily" (Col. 2:9).

The Nicene Creed is a prime example of systematic theology at its best. Systematic theology seeks to organize and summarize, not add or detract from, the biblical teaching. Systematic theologians then teach this doctrine to the church. These bishops in the early churches were systematic theologians. The creed the bishops constructed at Nicea was their gift to the church.

Stephen Nichols, "Christology in Context," Tabletalk Magazine (12/1/14)

Answer 2

All three members of the Trinity (or Godhead) are mentioned in 2 Corinthians 13:14. Jesus claimed to be in the Father, and the Father in Him.¹ Also, in the Gospel of John, we are told that in the beginning the Word existed, was with God and was God.² The author of the gospel later says that the Word became flesh and lived with humans ³, a reference to Jesus. So, Jesus is with God while being God, a hard concept to grasp but is inline with the doctrine of the Trinity. While Jesus is with God the Father and in Him, He is distinct entity (like the Father and Holy Spirit). He is the only God, and so is the Father and Holy Spirit. All three are united yet distinct. It's okay if you do not understand it thoroughly (I do not know anyone who does, I don't understand it fully either), just as long as you understand that it is a biblical concept.

Verses

¹ John 10:38, 14:10-11, 14:20
² John 1:1
³ John 1:14

Answer 3

Bible truth “is either expressly set down in scripture, or by good and necessary consequence may be deduced from scripture” (The Westminster Confession of Faith). Since the concept of homoousion is not explicitly stated in the Bible, the theory is that it is “good and necessary consequence” of what we read in the Bible.

Hebrews 1:3 is the only verse that refers to God's substance but it uses the word hypostasis which, at the time, had the same meaning as ousia (substance). However, the NASB translates hypostasis in Hebrews 1:3 more generally as “nature.” I prefer this term over “substance.” I do not think that the creed intends to say what God’s substance is, for humans are unable to understand His substance. I would like to read the word homoousion as saying that the Son’s nature is the same as the Father’s. As one of the comments on this page says:

Essence means nature. Essence is a property, not identity. We have or possess property we don't exist as property. God exists as a being with divine properties.

I think this understanding is confirmed by Eusebius of Caesarea, one of the main leaders at Nicaea, who, after the meeting, explained the meaning of homoousion as follows:

“Homoousios with the Father then simply implies that the Son of God has no resemblance to created things but is in every respect like the Father only who begat him.” Ecclesiastical History of Socrates Scholasticus I:8

Athanasius himself described homoousion as “signifying, that the Son was from the Father, and not merely like, but the same in likeness … inseparable from the essence of the Father, and He and the Father are one, as He has said Himself [John 10:30] … show that the Word was other than originated things. (Athanasius, De Decretis, 20,23)

But this question is about the Scriptural basis for the word homoousion. The basis that is provided by the creed itself is that the Son is “begotten from the Father, only-begotten.” The creed explicitly contrasts “begotten not made.” Therefore, to be begotten is different from being made. Since He is “begotten from the Father,” the creed infers that He is “from the substance of the Father” and “of one substance with the Father.” (I quoted from Earlychurchtexts.)

But the main Scriptural basis for the word homoousion is the interpretation that the Bible presents the Son as God Almighty; equal with the Father. This must be understood in contrast to what Arius taught. In the second and third centuries, Logos theology dominated the church. In that view:

God was “silent, remote in the infinity of his utter transcendence, acting only through the intermediacy of the Son or Word … had no direct contact with his creation; he was for ever and by definition insulated and isolated from it in the absolute serenity of an unchanging and unmoving perfection. (Alasdair I.C. Heron, "Homoousios with the Father," in The Incarnation, 68-69)

All the theologians of the second and third centuries ascribed to this view; even Origen. He attempted to put more emphasis on the Bible but Origen “still envisaged the Son as a subordinate agent of the Father and still treated him as an ingenious philosophical device” (Hanson). (The “ingenious philosophical device” refers to the logos-theology. See The Apologists.)

Arius was a traditional Logos-theologist. See how Alasdair describes Arius’ theology as exactly equivalent to the Logos theology. For the Logos theologians and for Arius, the Son was the intermediary through whom God created and redeemed.

In contrast, for Athanasius, what homoousios meant was this:

The reality of God himself is present with us and for us in Christ: “All that the Father is, the Son is also, except that the Father is Father, the Son, Son.” (Alasdair I.C. Heron, "Homoousios with the Father," in The Incarnation, 68-69)

This was the decisive difference between Athanasius and Arius and the real basis for the word homoousios.