John 17:23
John 17:2323I in them and You in Me—that they may be perfectly united, so that the world may know that You sent Me and have loved them just as You have loved Me.
A standard Watchtower answer to . If believers are to be one as the Father and Son are one, then that oneness must be unity of purpose rather than of essence — because Christians obviously do not share one being. The verse is used to reduce every claim of Father-Son unity to agreement.
The objection has real force and should be granted before it is answered. Jesus does pray that believers be one as he and the Father are one, and believers plainly do not share a single essence. The answer is that the comparison is about the pattern, not the degree. Jesus says "just as" of many things that hold at different levels — as the Father sent me, I sent them (17:18), and nobody concludes the apostles were sent from eternity. Then look at the language he uses for the divine side. "I in union with them and you in union with me." Elsewhere: "I am in the Father and the Father is in me" (14:10-11). That is mutual indwelling — each fully in the other, not merely agreeing with the other. Believers are brought into that relationship; they do not constitute it. This is where the perichoresis point helps, without the word. The three persons are not a committee coordinating three wills. They share one undivided will, exercised personally by each — which is why they cannot disagree, there being nothing to disagree about. That is a different thing from unanimity among separate agents. Compare , , .