What is the role of signs in John's gospel?

'Now Jesus did many other signs in the presence of the disciples, which are not written in this book; but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name.' Jn 20:30-31

The first half of John's gospel focuses on establishing the identity and salvation purpose of Jesus Christ. The 'signs' which John describes act as witnesses or evidence, testifying to Jesus' identity as the Son of God and the long-awaited Jewish Messiah. The signs in chapters 1-11 are "miraculous" events; moments when heaven and earth are connected (NT Wright). In this way, the signs show that Jesus brings a connection between men and God, and that He is the king of a kingdom that is not of this world, as He told Pilate.

The first sign is the transformation of water into wine at the wedding at Cana (chapter 2). Given the vision of John in Revelation of a great wedding feast once Christ has returned, this sign can be seen as a token of the new order of life inaugurated by Christ's coming, and a pre-figuring of the fulfilment of His kingdom in the new creation.

There are several healing signs: the official’s son (chapter 4), a paralyzed man (chapter 5) and a man born blind (chapter 9). The latter healing forms the longest narrative in John's gospel, and shows how Jesus' signs brought Him into direct conflict with the religious authorities. In a sad irony, the Pharisees are more concerned with the fact that the healing occurred on the Sabbath ('This man is not from God, for he does not keep the Sabbath' -Jn 9:16) than acknowledging the obvious truth, which the healed man points out: 'If this man were not from God, he could do nothing' (Jn 9:33). Not only do these miraculous healings indicate that the messianic age has arrived and Old Testament prophecy fulfilled, but in particular the healing of the blind man represents a vivid illustration of the spiritual blindness of the authorities. In this way the signs often interact with Jesus' teaching and discourses in John's gospel. Jesus' phrase 'I am the light of the world' (Jn 9:5) is illustrated by His ability to make the blind man see. The blind man also represents how people come to full salvation, in that he has a progressive understanding of who Jesus is, culminating in a full confession of faith by the end of the account.

Similarly, the feeding of the 5000 (chapter 6) complements Jesus' discourse and statement 'I am the bread of life' (Jn 6:35). Recorded in all four gospels as a major demonstration of Jesus' power as the Son of God, this miracle is shown in John's gospel to link Christ directly with God's provision of manna in the desert for Israel during their wilderness years. Ironically, the crowd mention this miracle themselves, without seeing the connection: 'what sign do you do, that we may see and believe you? What work do you perform? Our fathers ate the manna in the wilderness.' (Jn 6:30-31) Jesus therefore claims to be the 'bread from heaven', sent by the Father, and emphasises that true salvation is only found in Him. The graphic image 'Whoever feeds on my flesh and drinks my blood has eternal life' (Jn 6:54) expresses how a believer has total faith in Christ.

In walking on water (chapter 6), Jesus demonstrates His lordship over creation and His clear divinity. This is further enhanced by the sign of Lazarus being raised from the death (chapter 11). Jesus' great statement 'I am the resurrection and the life' (Jn 11:25) shows His power and ultimate authority over life and death. And therefore the greatest 'sign' in John's gospel is Christ's own resurrection, the proof that He is able to offer 'eternal life' as John so often repeats throughout the gospel, such as in Jn 3:16.