Jesus tells His opponents that when they have 'lifted up the Son of Man,' they will know that 'I am' and that He does nothing from Himself. Instead, He speaks as the Father has taught Him.
Jesus in Context
When You Have Lifted Up the Son of Man
Jesus says that the lifting up of the Son of Man will disclose His identity and demonstrate that His actions and teaching are inseparable from the Father.
Introduction
Historical and Cultural Context
John uses the language of Jesus being 'lifted up' with deliberate depth. The expression points to His physical elevation in crucifixion while also carrying the sense of exaltation. The same motif appears elsewhere in the Gospel, including John 3:14 and John 12:32-34.
Here the lifting up of the Son of Man is joined directly to recognition of Jesus' identity and to His claim that His actions and teaching originate in His relationship with the Father.
Why It Matters
The crucifixion, which might appear to Jesus' opponents to be His defeat, becomes in John part of the disclosure of who He is. The statement also guards against interpreting Jesus' claims as independence from the Father: He immediately says that He does nothing from Himself and teaches what the Father has taught Him.