Tractates on the Gospel of John

⁴ And then He added: “I in them, and You in me, that they may be made perfect in one.” Here He briefly intimated Himself as the Mediator between God and men. Nor was this said in any such way as if the Father were not in us, or we were not in the Father; since He had also said in another place, “We will come unto him, and make our abode with him;” and a little before in this present passage He had not said, “I in them and You in me,” as He said now; or, They in me, and I in You; but, “Thou in me, and I in You, and they in us.”

Accordingly, when He now says, “I in them, and You in me,” the words take this form in reference to the person of the Mediator, like that other expression used by the apostle, “You are Christ's, and Christ is God's.” But in adding, “That they may be made perfect in one,” He showed that the reconciliation, which is effected by the Mediator, is carried to the very length of bringing us to the enjoyment of that perfect blessedness, which is thenceforth incapable of further addition.

Hence the words that follow, “That the world may know that You have sent me,” are not, I think, to be taken as if He had again said, “That the world may believe;” for sometimes, to know, is also used in the same sense as to believe, as it is in the words He uttered some time before: “And they have known truly that I came out from You, and they have believed that You sent me.” He expressed the same thing by the later words, “they have believed,” as He had done by the earlier, “they have known.”

But inasmuch as He here speaks of the consummation, the knowledge must be taken for such, as it shall then be by sight, and not, as it now is, by faith. For an order seems to have been preserved in reference to what He said a little before, “that the world may believe;” while here it is, “that the world may know.” For although He said there, “that they all may be one,” and “may be one in us,” yet He did not say, “they may be made perfect in one,” and so subjoined the words, “that the world may believe that You have sent me;” but here He said, “That they may be made perfect in one,” and then added, not, “that the world may believe,” but, “that the world may know that You have sent me.”

For so long as we believe what we do not see, we are not yet made perfect, as we shall be when we have merited the sight of that which we believe. Most correctly, therefore, did He say in that previous place, “That the world may believe,” and here “That the world may know;” yet both there and here, “that You have sent me;” that we may know, so far as belongs to the inseparable love of the Father and the Son, that at present we only believe what we are on the way, by believing, to know.

And had He said, That they may know that You have sent me, it would be just of the same force as what He actually does say, “that the world may know.” For they are the world that abides not in enmity, as does the world that is foreordained to damnation; but one that out of an enemy has been transformed into a friend, and on whose account “God was in Christ reconciling the world unto Himself.” Therefore said He, “I in them, and You in me;” as if He had said, I in those to whom You have sent me; and You in me, reconciling the world unto Yourself through me.