Chapter eight begins with the story of the woman caught in adultery (7:53-8:11). The scribes and Pharisees interrupted Jesus' teaching in the Temple with a woman they accused of being an adulteress; Jesus simply told them that any man who had never sinned could enact the legal punishment of executing her, but that He would not condemn the woman (He also told her to "sin no more" (8:11)).
It should be noted that many scholars do not believe this story is part of the original Gospel writing. At the same time, however, many western Church Fathers refer to the story, and it is read for one of the feasts commemorating St. Mary of Egypt. Furthermore, the story is, in the words of one scholar, "true to the character of Jesus."
Jesus made an important statement in verse twelve: "I am the light of the world." St. Maximus the Confessor explains that this means Christ "is the brightness of souls, the one Who drives away the darkness of ignorance, and the one Who reveals mysteries that can be perceived only by the pure." Having the light of life, St. Gregory the Theologian says, means we should "approach (Christ) and be enlightened, and do not let your faces be ashamed, being signed with the true Light."
Despite His teachings, the Pharisees continued to doubt and misunderstand Jesus' identity as the Son of God (8:13, 25). The problem is that they understood neither from where He came nor to where He was going (8:14); they knew neither Christ nor His Father (8:19). Jesus' warning to them applies also to us today: if we do not believe that Jesus is the Son of God, then we will die in our sins (8:24). Such Orthodox teachers as St. John Chrysostom and Blessed Theophylact teach that this passage is directly tied to Holy Baptism, because sins can be washed away through baptism, but baptism ultimately does not help you if you do not believe in Him into Whom you are baptized (see Galatians 3:27).
This leads us to verses 31-51, where Jesus promised that people who become Jesus' disciples—who know His truth—shall be made free (8:31-32). What is this freedom? Blessed Augustine answers, "From what shall the truth free us except from death, corruption and changeableness, since truth itself remains immortal, incorrupt and unchangeable? But true immortality, true incorruptibility, true unchangeableness is eternity itself."
Unfortunately, the people at that time could not accept His truth. Instead, they actually accused Jesus of being possessed by a demon (8:48, 52) (which is particularly ironic since their disbelief in Christ proved that they were aligned with Satan rather than God (8:44-47))! They thought they had solid proof of Jesus' dishonesty: He said His followers would not taste death, and yet Abraham and the prophets had died (8:52-53). Jesus responded that Abraham saw Jesus' day and rejoiced (John 8:56). Many Church Father say this refers to the visitation of the three angels to Abraham in Genesis 18. St. Irenaeus adds that "Abraham was a prophet and saw in the Spirit the day of the Lord's coming and the dispensation of His suffering through Whom both he himself and all who trust in God would be saved."
Jesus could know this because He had seen Abraham; in fact, He said, "Before Abraham was, I AM" (8:58). The people reacted violently because, by applying God's divine name to Himself (see Exodus 3:13-15), Jesus claimed to be God.