John the evangelist, who has been the narrator of the story all along (2:22–25; 3:16–21, 31–36; 7:5), now sums up the meaning of Jesus’s public ministry (12:37–43). John 12:37 makes plain what all of early Christianity was forced to acknowledge: Jesus’s many signs fell on disbelief. John joins the other evangelists in drawing texts from Isaiah that must have been commonly used in the early church (Isa. 6:10; 53:1; cf. Matt. 13:14–17). Isaiah too found disbelief in Israel and attributed it to God’s sovereignty over revelation. John, however, has woven this theme into the entirety of the Book of Signs. Hence the unbelievers are unable to believe (John 12:39); God affects their perception (12:40). John, however, does not probe the mystery of the interplay between human responsibility and div…