In John’s Gospel, Jesus teaches us regarding the nature of heavenly things–in this case, the heavenly nature of his sonship–by speaking in terms of earthly things. He takes up language designed for speaking about things that are low and applies that language, with transformative significance, to things that are high.
The works that I do in my Father’s name bear witness about me (John 10:25).
John 1-12, the so-called “Book of Signs,” provides the Fourth Evangelist’s testimony regarding Jesus’ public ministry. According to John, the marvelous words and deeds that Jesus speaks and performs during his public ministry reveal the truth about his person. John 10:25 summarizes the revelatory logic at work in these chapters: “The works that I do in my Father’s name bear witness about me.” The works that Jesus performs bear witness about who he is.
The logic of revelation summarized in John 10:25 presupposes a specific concept of action, and an epistemological corollary, which I have summarized elsewhere. That concept of action is that certain kinds of agents produce certain kinds of effects. Fig trees produce figs. Grapevines produce grapes. And so forth (James 3:12). The epistemological corollary that follows from this concept of action is that “each tree is known by its fruit” (Luke 6:44). Certain kinds of effects reveal the presence of certain kinds of causes. Thus Jesus’ works, the wonderful life-giving signs that he performs, bear witness to who he is.
John’s claim that Jesus’ wonderful works are revelatory of Jesus’ identity is not a claim that their meaning is transparent. Indeed, even the most sympathetic observers of Jesus’ public ministry have a hard time grasping the significance of his transcendent identity merely by observing his transcendent actions. The riddle of Jesus’ identity is reflected in the questions his observers ask, “When the Christ appears, will he do more signs than this man has done?” (Jn 7:31), and in the (from a Johannine perspective) less than fully informed declarations they make, “Rabbi, we know that you are a teacher come from God, for no one can do these signs that you do unless God is with him” (Jn 3:2).
In John 10, Jesus’ opponents press him at this very point, demanding that Jesus resolve the riddle of his identity by telling them “plainly” whether he is “the Christ” (Jn 10:24; cf. 16:25: where revelation via “figures of speech” is contrasted with revelation that is “plain”). And though Jesus’ reply doesn’t evoke the response from Jesus’ opponents that John envisions for his ideal readers (but cf. Jn 10:42), Jesus’ answer is plain. The works that Jesus performs in his Father’s name manifest the truth about his filial identity: “I am the Son of God” (Jn 10:25, 36).
By this point in the Gospel, John has made it clear to his readers that Jesus is no mere earthly offspring of the heavenly Father (cf. Jn 1:12; 3:3, 5, 12). He is the heavenly Son of his heavenly Father (Jn 10:23, 27): the only-begotten Son of God who is above all because he was before all, who in the beginning was with God, who in the beginning was God (Jn 1:1, 14-15, 18, 30; 3:16, 31). John 10 confirms the transcendent nature of Jesus’ filial identity in the strongest way imaginable for a Jewish audience. Jesus is no mere teacher sent from God. Jesus is “one” with his Father, who is “greater than all” (Jn 10:29-30). The Father is “in” him and he is “in” the Father (John 10:38).