Jesus has returned to Jerusalem to celebrate the Feast of Tabernacles (or Booths). While he is there, he is teaching in the temple complex. A large group of Pharisees are questioning him about his identity. Some appear to even accept what he has to say about himself.
Starting in verse 31, however, he speaks directly to the Pharisees who have believed what Jesus has said about himself so far. A true disciple of Jesus will obey his every word and follow him for the long-term. In fact, it is only through following Jesus that a person can be set free from spiritual slavery.
The Pharisees answer that they don’t need to be freed from slavery because they are descendants of Abraham, and thus already children of God. Gerald Borchert explains, in vol. 25A, John 1–11, The New American Commentary,
In contrast to the Zealots, the Pharisees did not regard political liberty as the test of freedom. Being sons of God, a holy people, God’s possession, according to Deut 14:1–2, was for them the test of being free. So being circumcised, according to the rabbinic view, was the guarantee of escaping the bonds of Gehenna just as the people of Israel earlier escaped the bondage of Egypt (Exod. Rab. 19:81; 15:11). Or as the famed Rabbi Akiba reportedly stated concerning the Israelites, even the poor could be proud that they were ‘sons of kings’ because they were sons of the patriarchs (b. Šabb. 128).
Jesus corrects their understanding by pointing out that they are not children of God, but instead slaves to sin. In order for anyone to become a true child of God, they must be first freed from their slavery to sin. Only God’s Son, Jesus, has the power and authority to free them. Gerald Borchert adds:
He judged that they were slaves because they were sinners. Their confidence in their sense of internal liberty had been misplaced because being Jews and not Gentiles was no guarantee that they could avoid condemnation by God for their sinfulness. Yom Kippur (the Day of Atonement), which had just passed, should have reminded them that they too were sinners. In the presence of God both Jews and Gentiles stood condemned for sin (cf. Rom 3:23). Being sinful slaves before God, therefore, they were in need of a redeemer—one who could set them free. The Son who was personally sent by the Father was indeed capable of supplying them with such genuine freedom (John 8:36) because he was the Lamb who removed the sin of the world (1:29).
Knowing that some of the Pharisees are seeking to kill him, Jesus observes that his words to them are obviously not sinking in. In fact, the Pharisees are simply following the lead of their true spiritual father.
In verse 39 the Pharisees continue to argue with Jesus. They repeat that their true father is Abraham. Jesus responds that Abraham listened to God’s word and obeyed Him. The Pharisees are, instead, trying to kill a man whom God has sent, which again proves that their true father is not Abraham at all.
The Pharisees become incensed at Jesus’ accusation that they are not children of Abraham, and thus not children of God. Jesus explains that he knows this because God sent Jesus to the Jews, and they should therefore love Jesus because God sent him. Since the Pharisees don’t love Jesus, they cannot be children of God. Instead their true spiritual father is the devil!
Referring back to Adam and Eve’s fall in the Garden of Eden, Jesus reminds his audience that Satan is a liar and a murderer. There is no truth in Satan. The reason the Pharisees are not accepting Jesus’ claims is because Jesus is speaking God’s truth. Those who have Satan as their spiritual father are incapable of hearing God’s truth and accepting it.
Jesus challenges their stubborn rejection of his words by asking a rhetorical question: “Which one of you convicts me of sin?” D. A. Carson, in The Gospel According to John, The Pillar New Testament Commentary, explains Jesus’ purpose in asking this question:
If the best theological minds, however much they may dislike Jesus’ claims and dispute his teachings, find it impossible to marshall convincing reasons that would convict him of sin in (the heavenly) court, should they not begin to question themselves? Perhaps he is telling the truth, truth that is identified both with what Jesus says (v. 43) and with what God says (v. 47; cf. de la Potterie, 1. 61–64).
At this point in the dialogue, the Pharisees begin personal attacks. They accuse Jesus of belonging to the hated Samaritans and of being demon-possessed! Jesus denies being demon-possessed and reminds them that they dishonor God by dishonoring him.
In verse 51, Jesus proclaims, “Truly, truly, I say to you, if anyone keeps my word, he will never see death.” The Pharisees, thinking Jesus is referring to physical death, mock him by reminding him that Abraham died, not to mention all the other great prophets. Just who does he think he is? Does he think he’s greater than Abraham?
Jesus answers, “Your father Abraham rejoiced that he would see my day. He saw it and was glad.” The Pharisees again ridicule Jesus by pointing out the obvious fact that Jesus could not have seen Abraham, who had lived roughly two thousand years before, given that Jesus was not even fifty years old.
Jesus responds with a shocking statement: “Truly, truly, I say to you, before Abraham was, I am.” Upon hearing him, the crowd picks up stones to kill him, but Jesus slips away before they could stone him to death.
Why did the Jews want to kill him? Quite simply, Jesus was claiming to be equal to God. Gerald Borchert writes that Jesus’ pronouncement
was a reminder of the claims for God in the Old Testament over against creation (cf. Ps 90:2; Isa 42:3–9) and of the self-designation for the comforting God of Isaiah (41:4; 43:3, 13). The claim of Jesus, therefore, was clearly recognized from the Jews’ perspective to be a blasphemous statement they could not tolerate. Accordingly, they again made their judgment call, and their verdict implied death by stoning (John 8:59; cf. Lev 24:11–16; 1 Kgs 21:10–13).
Craig Keener, in The IVP Bible Background Commentary: New Testament, also notes:
’I am’ was a title for God (Ex 3:14), which suggests that Jesus is claiming more than that he merely existed before Abraham. This title of God may have been fresh on the minds of Jesus’ hearers at the feast: during the Feast of Tabernacles, the priests were said to utter God’s words in Isaiah: ‘I am the Lord, I am he’ (Is 43:10, 13).