Charles Ellicott Commentary John 17:23

"I in them, and thou in me, that they may be perfected into one; that the world may know that thou didst send me, and lovedst them, even as thou lovedst me." — John 17:23 (ASV)

I in them, and you in me.—These words are best regarded as a parenthesis more explicitly setting forth the thought of the union of the Father, the Son, and the believer. The thought is continued from the last verse, That they may be one even as we are one: I in them, and You in Me, that they may be made perfect in one. It is the thought which the words of Christ have uttered again and again, and which we still feel that no words can utter.

The disciples heard these words immediately after they heard the allegory of the true vine (John 15:0). The fullest meaning of separate words and phrases in these chapters is best arrived at by remembering that they were not uttered as separate words and phrases, but were spoken as a whole and should be read as a whole; indeed, the most unfathomable of them were spoken in prayer from the Son to the Father.

That they may be made perfect in one.—Better, . . . unto one. The unity is the result of their being made perfect. (Compare to Notes on Hebrews 10:14, 1 John 2:5, 1 John 4:12, and 1 John 4:17–18.)

And that the world may know that you have sent me.—Better, . . . did send Me. Compare to John 17:21. “That the world may know” (recognize) here is parallel to “that the world may believe” in the earlier verse. We are to regard it, therefore, as another instance of the repeated expression of the fullness of thought; and this is borne out by the parallel in John 13:35 and John 14:31.

The thought introduced here, of the conviction of the unbelieving world, seems to be opposed to the context. The prayer is that the world, seeing in its midst the power which binds people together in unity, may believe and know that this is of God, who sent Christ into the world, and may accept for themselves the message of love which the “Sent of God” has brought to them. (Compare to Note on John 3:16.)