I now turn to what is without a doubt the most popular interpretation of John 10:30 other than the traditional Trinitarian understanding, namely, the view that Jesus was asserting only that he and the Father were one in purpose. I should state at the outset that everyone agrees that from a New Testament perspective Jesus and the Father are one in purpose. The issue is whether the unity of which John 10:30 speaks is specifically a unity of purpose rather than a unity of divine power, nature, or identity. In other words, the claim to be considered here is whether John 10:30 means nothing more than that Jesus is united in purpose with the Father.
Those who promote the “one in purpose” view in order to combat Trinitarian theology can point out that some mainstream Christian scholars have also interpreted John 10:30 in this way. J. H. Bernard, in the older ICC commentary on John, explicitly takes this position:
A unity of fellowship, of will, and of purpose between the Father and the Son is a frequent theme in the Fourth Gospel (cf. 5:18,19; 14:9,23 and 17:11,22), and it is tersely and powerfully expressed here; but to press the words so as to make them indicate identity of OUSIA, is to introduce thoughts which were not present to the theologians of the first century (A Critical and Exegetical Commentary on the Gospel According to St. John, International Critical Commentaries [Edinburgh: T & T Clark, 1928]).
Similarly, R. V. G. Tasker, in his commentary on John, says that although the orthodox church fathers cited this verse in support of the doctrine that Christ was of one substance with the Father, the statement seems however mainly to imply that the Father and the Son are united in will and purpose (The Gospel According to St. John, Tyndale New Testament Commentaries [Grand Rapids: Eerdmans, 1960], 136). Other commentators make similar statements.
Anti-Trinitarians often quote John Calvin in support of the same point. However, Calvin really does not agree with the one in purpose view. He writes:
He intended to meet the jeers of the wicked; for they might allege that the power of God did not at all belong to him, so that he could promise to his disciples that it would assuredly protect them. He therefore testifies that his affairs are so closely united to those of the Father, that the Father’s assistance will never be withheld from himself and his sheep. The ancients made a wrong use of this passage to prove that Christ is (homoousios) of the same essence with the Father. For Christ does not argue about the unity of substance, but about the agreement which he has with the Father, so that whatever is done by Christ will be confirmed by the power of his Father (Commentary on the Gospel According to John, trans. William Pringle [Grand Rapids: Eerdmans, 1949; orig. 1847], 416).
Calvin nuances his position here rather finely. On the one hand, he points out that in context Christ is speaking of his unity of power with the Father–his claim that the power of God did truly belong to him–so that he could guarantee the eternal salvation of his people despite all manner of spiritual attacks against them. This is, then, for Calvin a oneness of power, not merely a oneness of purpose. The Son’s power to preserve his people is the power of God, not the power of a lesser, weaker creature. On the other hand, Calvin argues that the church fathers went beyond the point of the passage by trying to deduce from it the technical theological concept of homoousios that the Father and the Son are of one essence or being. His point seems to be that the words are one, in and of themselves, are not sufficient to establish that doctrine; such an implication goes beyond the demonstrable meaning of the text.
One may agree with Calvin without abandoning a Trinitarian interpretation of the passage. After all, Calvin was himself a Trinitarian, and his way of reading the passage as a whole is patently Trinitarian: the Father and the Son are distinct persons, yet the Son wields the power of God no less than the Father. Calvin goes on to comment on the reaction of the Jewish opponents of Jesus in John 10:33 as follows:
They argue therefore that Christ is a blasphemer and a sacrilegious person, because, being a mortal man, he lays claim to Divine honor. And this would be a just definition of blasphemy, if Christ were nothing more than a man. They only err in this, that they do not design to contemplate his Divinity, which was conspicuous in his miracles.
Thus, Calvin clearly supports the one in power view, although he cautiously warns against trying to prove too much from the words are one in John 10:30. This is a respectable and thoughtful position. As I explained in Part II, I think the recognition that in verse 28 Christ speaks of himself as God, using the wording of Deuteronomy 32:39, puts the words are one in verse 30 in a somewhat different light, strongly suggesting (at least) an allusion to the Shema in Deuteronomy 6:4. With this additional information regarding the context of John 10:30–which Calvin does not mention or seem to have noticed–we are on stronger ground in seeing Jesus’ statement as a claim to be one God with the Father. That is not an explicit or simply direct proof of homoousios, but it is a short step indeed to that implication.
The point may be made in a different way. Calvin clearly understands John 10:30 in its context in the Gospel of John in a Trinitarian way, as speaking of his oneness of divine power with the Father, but is simply being careful not to read off “one substance” from the simple word one. Rather, Calvin sees the deity of the Son implicit in the statement given its context. Furthermore, Calvin places the focus or emphasis in John 10:30 on the Son’s divine activity, the concrete expression of his deity in our salvation, rather than on the metaphysical or ontological definition of the Son’s nature. According to Calvin, Christ was not seeking to explain his nature but to respond to the unbelieving Jews’ attacks against him. Thus, Calvin comments on John 10:36,
Christ does not now argue what he is in himself, but what we ought to acknowledge him to be, from his miracles in human flesh. For we can never comprehend his eternal Divinity, unless we embrace him as a Redeemer, so far as the Father hath exhibited him to us.
Some contemporary commentators likewise caution us against reading too much explicitly into the word one or this single sentence on its own, while at the same time arguing that Jesus’ statement in the larger context of the Gospel of John does connote or imply a claim to deity. For example, Andrew Lincoln observes that the force of John 10:30 in its immediate context is that Jesus and the Father are one in securing the safety of the sheep in their care.
There may be two agents but their protecting hand is one. This indication of Jesus’ full unity with the Father in his divine work of salvation has further implications for Jesus’ identity, and so later Christians who used this text in Christological debates and formulations about the metaphysical unity of the Father and the Son need not be faulted as totally misguided.
Lincoln points out that such further implications are confirmed by the rest of what the Gospel says about Christ’s relation to God, especially in the Prologue. “Father and Son are united in the work of salvation because they are united in their being” (Andrew T. Lincoln, The Gospel According to Saint John, Black’s New Testament Commentaries 4 [Peabody, MA: Hendrickson; New York and London: Continuum, 2005], 306).
D. A. Carson likewise argues that John 10:30 read in the broader context of what the rest of the Gospel says about John including its explicit affirmations that Christ is God (John 1:1, 18; 20:28). As for the immediate context, Carson comments that “the oneness of will and task, in this context, is so transparently a divine will, a divine task (viz. the saving and preserving of men and women for the kingdom) that although the categories are formally functional some deeper union is presupposed” (D. A. Carson, The Gospel According to John, Pillar NT Commentary [Leicester, England: Inter-Varsity Press; Grand Rapids: Eerdmans, 1991], 394-95).
The point here is this: One can agree that the focus of John 10:30 is practical or even “functional” without ignoring or denying that the statement has ontological implications for our understanding of the person of Christ. I agree with those commentators who argue that the statement has clear implications in context of the deity of Christ even if one does not recognize John 10:30 as an explicit claim to deity. Nor is this way of reading John 10:30 dependent on or original with the orthodox church fathers embroiled in the Arian controversy. Almost a century before the Arian controversy, the biblical scholar Origen of Alexandria had this to say about John 10:30:
Our Savior and Lord in his relation to the Father and God of the universe is not one flesh or one spirit but something higher than flesh and spirit, namely, one God. The appropriate word when human beings are joined to one another is flesh. The appropriate word when a righteous person is joined to Christ is one spirit. But the word when Christ is united to the Father is not flesh or spirit but more honorable than these God. This then is the sense in which we should understand “I and the Father are one” (Origen, Dialogue with Heraclides 3-4, quoted in Joel Elowsky, ed., Ancient Christian Commentary on Scripture: John 1-10 [Downers Grove, IL: InterVarsity Press, 2007], 358).