I and my Father are one – John 10:30
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 (ὁμοούσιος) 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.
Source: Calvin’s Commentary on the Bible
The great question here is, whether these words are to be understood of the unity of the Father and Son, as to their same monadical essence, or (as many of the Ante-Nicene Fathers did interpret them) of an unity in will, design, affection and concord? That they could not be intended to declare an unity of their individual essence, seems highly probable, both from the context; from the like expressions in the Scripture; and from the very nature of the thing. First, from the context; for there our Savior saith, “The works that I do in my Father’s name”–that is, by his authority and power imparted to me–”bear witness of me” (ver. 25); which words are evidently repugnant to a numerical unity of essence in them both; since where the essence is one, the actions must be one, and done by the same authority and power. To which add, that the words, “I and my Father,” are words plainly importing two persons; for the word Father is personal, and the word I is a pronoun personal; so that if these two are one and the same God by virtue of this text, they must be one in person as well as essence. Moreover (ver. 29), “My Father which gave them me” (saith Christ) “is greater than all;” which again destroys the numerical unity of essence betwixt both; since no one essence can give any thing to itself, and much less a divine and all-perfect essence. Nor can one essence be greater than itself; whereas our Lord expressly saith, “My Father is greater than I” (John xiv. 28). Secondly: This will be farther evident from the parallel expressions used by our Lord in the same Gospel, where he prays that his disciples “may be one, as thou, Father, art in me, and I in thee; that they might be made perfect in one:” and yet, doubtless, he could not pray that his disciples might be one in essence with the Father and Son, but only that they might be one by having the Spirit of the Father and Son dwelling in them. In which sense, Athenagoras says the Father and Son are one, viz. ἐνότητι τοũ πνεύματος, by unity of the Spirit. Thus Origin interprets this verse. For, having cited these words, “I and my Father are one,”– If any one, saith he, is disturbed at these expressions, as if we favoured the opinion of the Noetians, who deny the Father and the Son to be δύο ὑποστάσεις, two singular existences, let him consider this text (Acts iv. 34), “All that believed were of one heart and one soul,” and then he will understand this, “I and my Father are one thing:” we serve, therefore, ὡς ἀποδεδώκαμεν, as we formerly explained it, one God the Father, and the Son; we worship the Father of the truth, and also the Son, who is the truth, being indeed two things in subsistence, but in agreement and consent and sameness of will, they are one. Here, indeed, he only saith we worship the Father of the truth, and the Son, who is the truth and wisdom; but in his comment on John (p. 70), he adds, that the Father is πλείων, μείζων ἀλήθεια, a fuller and greater truth, and, being the Father of wisdom, is greater and more excellent, as he is Wisdom, than the Son. Then he proceeds (p. 387) to shew, that among the multitude of believers, some, differing from the rest, rashly affirmed, as the Noetians did, that our Saviour was the God over all; which, saith he, we Christians, or we of the church, do not believe, as giving credit to the same Saviour, who said, “My Father is greater than I.” And, lastly, he saith (p. 38), We Christians manifestly teach, that the Son is not stronger than the Father, who is the Creator of the world, ἀλλ’ ὑποδεέστερος, but inferior in power to him; which words afford the clearest demonstration, that the church of that age did not believe that our Saviour was ὁ ἐπὶ πᾶσι Θεὸς, the supreme God, or one of the same numerical essence with the Father; and therefore could not interpret those words of such an unity, but only of an unity of concord, mind and will. Hence, in his comment upon St. John (p. 227), he saith, that this unity of will is the cause of why Christ said, “I and my Father are one;” and in his next page adds, that the will which is in Christ is the image of the first will, and the divinity which is in Christ is the image of the true divinity. Novatian is, if possible, still more express in this interpretation: for, in answer to the objection of the Sabellians from this place, he saith, that unum, being here put in the neuter gender, denotes not an unity of person, but a concord of society between them; they being deservedly styled one, by reason of their concord and love, and because whatsoever the Son is, he is from the Father. The apostle, saith he, knew this unity of concord with the distinction of persons, by writing to the Corinthians thus: “I have planted, Apollos watered, but God gave the increase.” For who understands not that Paul is one person and Apollos another? and that they had divers offices, one to plant and another to water? And yet the apostle Paul saith of these two, ἔν εἰσι, “they are one,” though, as to the distinction of persons, they are two; with other things of like nature. And here it is to be observed, that Pamelius’s note upon these words is this: Nempe in hoc loco, non satis accurate scribere Novatianum, quod nullam essentiœ Patris, et Filii communicationem adferat, sed exemplum ab apostolo unitati essentiœ veluti contrarium; in quo certe hallucinatum fuisse auctorem non vereor dicere, quum postea ecclesia in diversis conciliis, diversum definiverit. That is, Novatian did not write accurately in this place, as making no mention of the communion of the essence betwixt the Father and the Son, but introducing an example from the apostle, as it were, contrary to it; in which thing I doubt not to pronounce him erroneous, seeing the church afterwards in divers councils defined the contrary. And yet it is certain that many of the Ante-Nicene fathers in effect said the same thing: for Justin pronounces the Son to be ἕτερος ἀπὸ τοῦ Πατρὸς ἀριθμῷ οὐ γνώμῃ, another from the Father in number, but not in consent. And his reason follows thus, because he never would do any thing but what ὁ τὸν κόσμον ποιήσας, ὑπὲρ ὃν ἄλλος οὐκ ἔστι θεὸς, βεβόληται καὶ πρᾶξαι καὶ ὁμιλῆσαι, the Maker of the world would have him do and speak. Where, first, this God the Father is plainly styled another in number from him that made the world; and, secondly, the Son is represented as one not doing his own will, but being in all things subservient to, and delivering the words of that God, from whom he is thus distinguished. Lactantius saith, that the Father and Son are one, quia unanimes incolunt mundum, because they unanimously dwell in the world. Eusebius pronounces the Father and Son to be one, οὐ καθ’ ὑπότασιν ἀλλὰ κατὰ τὴν κοινωνίαν τῆς δόξης, not as to the essence, but as to communion of glory. And lastly, the council of Antioch pronounceth the Father, Son and Holy Ghost to be τρία μὲν ὑποστάσει τῆ δὲ συμϕωνίᾳ ἓν, that is, three in subsistence, but one only in consent or concord. Terullian declares, in answer to this objection of the Sabellians, that these words, “I and the Father,” duorum esse significationem, signify two; and then adds, that unum neutrali verbo non pertinet ad singularitatem, sed ad unitatem, ad similitudinem, ad conjunctionem, ad delectionem Patris qui Filium diligit; et ad obsequium Filii qui voluntatis Patris obsequitur: which last words shew that it is impossible that this text should be interpreted of the numerical essence or unity of the Father and Son; seeing one and the same essence cannot be obsequious or obedient to itself. And yet there is nothing more common among the Ante-Nicene fathers, than to say with Novatian, who having affirmed that the Son, obedierit Patri, et obediat, always did and always doth obey the Father, thence make this inference–Quid tam evidens esse ptest hunc non Patrem esse, sed Filium, quam quod obediens Patri Deo proponitur? What more evidently shews that Christ is not the Father, but the Son, than this, that Christ is obedient to the Father? (Cap. xxiii.) And again (Cap. xxx.), Filius nihil ex arbitrio suo gerit, nec ex concilio suo fecit, nec a se venit; sed imperiis paternus omnibus, et preceptis obedit, ut quamvis probet illum nativitas Filium, tamen morigera obedientia asserat ipsum paternæ voluntatis, ex quo est, ministrum. Ita dum se Patri in omnibus obtemperantem reddit, quamvis fit et Deus, unum tamen Deum Patrem de obedientia sua ostendit, ex quo et traxit, originem; that is, in short, the Son of God, by his dutiful obedience to all his Father’s commands, and to his will (he doing nothing by his own will and counsel), by this demonstrated, that though he was God, yet the Father, from whom he came forth, and whom he obeyed, was the one God, even that one God, of whom he saith, Nos scimus et legimus et credimus et tenemus, unum esse Deum, qui fecit eælum pariter ac terram, quoniam nec alterum novimus, aut noscere (cum multus sit) aliquando poterimus; that is, we Christians know, believe and hold, that there is one only God, the Creator of heaven and earth; nor know we, nor can we know any other, because there is no other. And again, God the Father is unus Deus, cujus neque magnitudini, neque majestati, neque virtuti quicquam non dixerim præfferri, sed nec cimparari potest; that is, that one god, to whose greatness, majesty and power, nothing can be compared (Cap. xxx.). And indeed all the Greek fathers, from Justin to Eusebius inclusive, do frequently inform us that the Son did ὑπηρετεῖν τῷ θελήματι τοῦ Πατρὸς, obey the will of the Father, that he did ὑπουργεῖν, διακονεῖν, ὑπηρετεῖν, minister, and was subservient to him. And all that writ in Latin, from Tertullian to Lactantius inclusively, that he did Patris voluntati administrare, administer to the will of the Father; that he did obedire in omnibus Patri, obey the Father in all things; that the Son voluntati Patris fidelitur paret nec unquam faciat aut fecerit, nisi quod Pater aut voluit aut jussit, faithfully obeyed the will of his Father, and never doth or would do any thing but what the Father willed or ordered him to do (Lb. iv. C. xxix.). It being therefore certain, that one and the same essence can have but one and the same will, and that one singular and numerical essence cannot administer to the will, obey, and be subservient to the will and commands of another; hence it is demonstratively evident that he who does so, cannot have the same numerical essence and will with the Father.
Source: The Last Thoughts of Dr. Whitby