As a historical source for the ministry of Jesus of Nazareth (c. 6–4 BCE—c. 30 CE), some scholars dismiss the Gospel of John.

See Why is There Doubt Over the “I am” Statements in the Gospel of John?
See The Gospel of John as Historiography: Topography, Chronology, Selectivity, Narrative Asides, and Eyewitness Appeal
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Problematically, in their view, the Johannine Jesus makes explicit claims to be equal with God that are not paralleled in the synoptic gospels of Mark, Matthew, and Luke (Ehrman 2014, 124–126). John’s gospel also fails when the criteria of authenticity are applied.

The value of John’s gospel’s historicity has indeed been contentious, although more recent scholarship has come to appreciate its significance as a historical source (Burge 2008, 807). Over the later decades of the twentieth century, many scholars came to hold positive evaluations of John’s gospel (Carson 1981; Thompson 1988; Wenham 1996)

John’s Differences from the Synoptics

Indisputably, John’s gospel evidences many differences from the synoptics. As Michael F. Bird writes, “Going from the Synoptics to John is like going from New York in peak hour traffic on Friday afternoon to a Rose Bowl parade on January 1. While many similarities exist between John and the Synoptics, John is clearly in a class of his own and is doing his own thing. That gospel has a unique texture, a distinctive feel, and a definite set of objectives” (2015, 110).

The wine miracle at Cana (2:1-11), temple cleansing (2:13-22), conversation with the pharisee Nicodemus (ch. 3) and the Samaritan woman (ch. 4), healing of paralyzed and blind men (ch. 5, 9), raising of Lazarus (ch. 11), foot-washing episode (ch. 13), and day of Jesus’ crucifixion (19:14) are unique traditions included in John’s gospel and absent from the synoptics.

The sayings of Jesus differ quite extensively, such as in, for instance, the Garden of Gethsesmane before his arrest. In John’s account, Jesus is presented as praying at length and with confidence for twenty-six verses (ch. 17), which contrasts with the agony he experienced as described by the synoptics (Mark 14:33–36; Matt. 26:37–39; Luke 22:41).

Given these differences, when John departs from the synoptic tradition, many understandably wonder if his contribution is reliable.

Similarities with the Synoptics

John’s gospel is not, however, so different that it should be considered detached from the synoptic tradition entirely.

All four canonical gospels agree that Jesus is God’s Son and that, as the Son, he is the divine agent and part of the divine identity. John’s theology of divine sonship is distinctive in some areas but remains compatible with the synoptics. The best explanation is that the author drew from a parallel and interlocking pool of tradition. Bird explains that,

John’s claim that Jesus is “equal with God” (John 5:18) and “one with the Father” (10:18) is simply verbalizing what is already assumed by the Synoptics Gospels, namely, that Jesus has a unique filial relationship with Israel’s God and Jesus possessed an authority equal to that of God (2014, 111).

John’s ideas are not resourced in Greek philosophy through an extended encounter with Hellenism but rest solidly within a Jewish conception of God’s activity within the world. In his famous verse of 1:14 (“The Word became flesh and made his dwelling among us. We have seen his glory, the glory of the one and only Son, who came from the Father, full of grace and truth.”  John asserts that just as God’s glory dwelt in the temple and God’s wisdom dwelt in the Torah, so now God’s word dwells in human flesh.

John’s high Christology was not overpowered by Hellenistic philosophy but remains a thoroughly Jewish story, with its own historical contribution, and it makes an authentic interpretation of the life of Jesus as validated by the testimony of the “beloved disciple.” Bird argues that the “real historical question” for those who dismiss John’s record is to convincingly explain why there are so many parallels between the synoptics and John and how such an interpretation of Jesus as “equal with God” arises in the first place (2014, 109).

Although John interprets the Jesus tradition in a specific theological trajectory, he shares with the synoptics a conception of Jesus as the Messiah and one-of-kind Son of God, in whom God is definitively revealed.

New Confidence in John’s Historicity

In 1959, a British scholar named J. A. T. Robinson (1919–1983) published an essay describing a shift in how scholars were viewing John’s gospel. His volume, The Priority of John, argued that John contained material that was as early as any synoptic story and that it was trustworthy. John’s material predated the Jewish War of 66–70 CE.

It was recognized that just because John’s material departed from the synoptic tradition, it did not mean that its independent material was inauthentic. In 1963, the well-known Cambridge New Testament scholar C. H. Dodd (1884–1973) published a lengthy analysis, concluding that “behind the Fourth Gospel lies an ancient tradition independent of the other gospels, and meriting serious consideration as a contribution to our knowledge of the historical facts concerning Jesus Christ” (1976, 423). According to New Testament historian Michael Labahn,

The question of the gospels and their sources as base for a reconstruction of the life and teaching of Jesus became a much broader-based approach in recent research. The Gospel of John as well as its traditions and extra-canonical gospel texts were recognized as possible sources that may contain reliable information mainly to reconstruct the teaching of Jesus (see, e.g., Crossan)… as a creative interpreter of Jesus tradition and in his christologically elaborated story, the fourth Evangelist preserves historical memories of Jesus: e.g. his openness to women (cf. John 4) (2008, 940).

Gary M. Burge writes that the “starting point for the scandal of the Fourth Gospel in the Hellenistic world was its absolute commitment to history. John would not compromise the notion that God had done something in Christ in history” (2008, 807).

The Jesus of John is not only deified but also depicted as a flesh and blood human being, hence John’s Christology never letting the reader assume that Jesus lacks humanity. He thirsts, hungers, weeps, and, in the culmination of his ministry, dies by a common method of Roman execution. In Burge’s view, 

[John’s] theological reflexes did not incline him to generate stories presenting theological ideals that did not happen in time. In other words, John’s incarnational theology made him predisposed to a commitment to history, to “flesh,” to real characters in whom divine events were transpiring. But John has another commitment. Again and again the gospel refers to “truth” (John 4:24; 8:32; 14:17), affirming the trustworthiness of its account. Moreover, it refers as well to the importance of “witness,” anchoring the validity of its story in a person (the Beloved Disciple) who had “seen” and “touched” and “heard” this reality (2008, 807).

Biblical scholar Craig A. Evans concludes that “The New Testament’s deification of Jesus Christ, as seen especially in the theologies of Paul and the fourth evangelist, has its roots in the words and activities of the historical Jesus” (1996, 67). To simply dismiss the gospel of John as historically suspect is now passé (Burge 2008, 297).

References

Bird, Michael F. 2014. How God Became Jesus: The Real Origins of Belief in Jesus’ Divine Nature—A Response to Bart Ehrman. Grand Rapids: Zondervan Academic. (Apple Books).

Boring, M. Eugene. 1999. “Markan Christology: God-Language for Jesus?” New Testament Studies 45:451–471.

Carson, D. A. 1981. “Historical Tradition in the Fourth Gospel: After Dodd, What?” In Gospel Perspectives vol. 2: Studies of History and Tradition in the Four Gospels, edited by R. T. France and David Wenham, 83–145. Sheffield: JSOT Press. 

Dodd, C. H. 1976. Historical Tradition in the Fourth Gospel. Cambridge: Cambridge University Press.

Evans, Craig A. 1996. “The Historical Jesus and the Deified Christ: How Did the One Lead to the Other?” In The Nature of Religious Language: A Colloquium, edited by S. E. Porter, 47–67. Sheffield: Sheffield Academic Press.

Johansson, Daniel. 2010. “Kyrios in the Gospel of Mark.” Journal for the Study of the New Testament 33:101–124.

Labahn, Michael. 2008. “Historical Criticism (or Gospels as Sources).” In The Routledge Encyclopedia of the Historical Jesus, edited by Craig A. Evans, 930-948 (Apple Books). Routledge.

Thompson, M. M. 1996. “The Historical Jesus and the Johannine Christ.” In Exploring the Gospel of John, edited by R. Alan Culpeppar and C. Clifton Black, 21-42. Louisville: Westminster John Knox.

Wenham, David. 1998. “A Historical View of John’s Gospel.” Themelios 23:5–21.