As He did in 3:6, Jesus contrasted the Spirit who gives life with the flesh that profits nothing. Spiritual life comes only when the Holy Spirit imparts Christ’s life to the believer (Gal. 2:20; Col. 3:3–4). It does not come through “the will of the flesh” (1:13), which as R. V. G. Tasker notes, “signifies the outward to the exclusion of the inward, the visible apart from the invisible, the material unrelated to the spiritual, and the human dissociated from the divine” (The Gospel According to St. John, The Tyndale New Testament Commentaries [Grand Rapids: Eerdmans, 1975], 96). The Lord exhorted those who took issue with eating His flesh (v. 52) to focus instead on partaking of His Spirit (vv. 53–58).
Of course, no one can do that apart from hearing and obeying the words that Jesus has spoken, which, He declared, are spirit and are life. It is Jesus’ words that reveal who He really is. As noted earlier, accepting or rejecting those words separates true and false disciples. True disciples continue in His Word (8:31), which abides in them (15:7; cf. Jer. 15:16; Col. 3:16; 1 John 2:14); false disciples ultimately reject His word (8:37, 43, 47). To embrace Jesus’ words is to receive Him, for they reveal His person. Thus the Bible teaches that salvation comes through the agency of the Word of God:
Now the parable is this: the seed is the word of God.… The seed in the good soil, these are the ones who have heard the word in an honest and good heart, and hold it fast, and bear fruit with perseverance. (Luke 8:11, 15)
But He answered and said to them, “My mother and My brothers are these who hear the word of God and do it.” (Luke 8:21)
In the exercise of His will He brought us forth by the word of truth, so that we would be a kind of first fruits among His creatures. (James 1:18)
Therefore, putting aside all filthiness and all that remains of wickedness, in humility receive the word implanted, which is able to save your souls. (James 1:21)
For you have been born again not of seed which is perishable but imperishable, that is, through the living and enduring word of God. (1 Peter 1:23)
63 That Jesus was speaking metaphorically when he said that a person must eat his flesh and drink his blood (v. 54) is now made clear. It is the Spirit who “gives life.” He is the one who provides life eternal. “The flesh counts for nothing”; it is totally unable to provide spiritual sustenance. “Flesh” (sarx, GK 4922) here is “the earthly part of man, man as he is by nature, his intellect remaining unilluminated by the revelation of God” (Lindars, 273). Little wonder that it cannot produce life. Life comes from hearing and absorbing the words of Jesus. His words are “spirit and … life.” It is through his words that the Spirit communicates life to the person of faith. We are reminded of Jeremiah’s testimony that when the Lord’s words came, he ate them, and they were his joy and heart’s delight (Jer 15:16). Even though some of Jesus’ followers had listened to what he had to say, they still did not believe. There is a hearing of the ears only. To hear in such a way is to acknowledge the voice but to refuse the message. There is also a hearing of the inner person. To hear in this way is to take the next step and actually commit oneself to the message. When this happens, it is the Spirit giving life through the words of Jesus. This same phenomenon is true today. To read God’s Word and find one’s heart “strangely warmed” (as John Wesley put it) is to discover oneself in actual communication with the Spirit, whose role it is to illumine the believing heart.