12:39 For this reason they could not believe, 1 because again Isaiah said,
12:40 “He has blinded their eyes
and hardened their heart, 2
so that they would not see with their eyes
and understand with their heart, 3
1 sn The author explicitly states here that Jesus’ Jewish opponents could not believe, and quotes Isa 6:10 to show that God had in fact blinded their eyes and hardened their heart. This OT passage was used elsewhere in the NT to explain Jewish unbelief: Paul’s final words in Acts (28:26-27) are a quotation of this same passage, which he uses to explain why the Jewish people have not accepted the gospel he has preached. A similar passage (Isa 29:10) is quoted in a similar context in Rom 11:8.
2 tn Or “closed their mind.”
3 tn Or “their mind.”
4 tn One could also translate στραφῶσιν (strafwsin) as “repent” or “change their ways,” but both of these terms would be subject to misinterpretation by the modern English reader. The idea is one of turning back to God, however. The words “to me” are not in the Greek text, but are implied.
6 tn Grk “his”; the referent (Christ) has been specified in the translation for clarity. The referent supplied here is “Christ” rather than “Jesus” because it involves what Isaiah saw. It is clear that the author presents Isaiah as having seen the preincarnate glory of Christ, which was the very revelation of the Father (see John 1:18; John 14:9).
sn Because he saw Christ’s glory. The glory which Isaiah saw in Isa 6:3 was the glory of Yahweh (typically rendered as “Lord” in the OT). Here John speaks of the prophet seeing the glory of Christ since in the next clause and spoke about him, “him” can hardly refer to Yahweh, but must refer to Christ. On the basis of statements like 1:14 in the prologue, the author probably put no great distinction between the two. Since the author presents Jesus as fully God (cf. John 1:1), it presents no problem to him to take words originally spoken by Isaiah of Yahweh himself and apply them to Jesus.