From The Five Gospels (Funk, Hoover, 1993, Harper Collins):

• John 10:30: ranked as not going back to Jesus, due to the “voice” and having no common ground with the aphorisms and parables of Jesus found in the synoptics.
• John 8:58: ranked as not going back to Jesus. They mention that Christian dialogue around Abraham is part of Christian community’s attempt to “establish its claims over against the Jewish community, which continued to claim a privileged relationship to God based on the Hebrew scriptures.”

These sayings fail the the major criteria, as outlined by Dale Martin, used to determine if something was likely historical (https://youtu.be/d_dOhg-Fpu0?si=guAXsSrRg4LJtJRi):

• Multiple attestation
• Dissimilarity
• Social coherence
• Coherence with the other criteria.

Ehrman in Jesus also claims that the historical Jesus likely viewed himself as the messiah in a future, temporal kingdom ushered in by God, but he didn’t view himself as God incarnate.

The differences between John and the synoptics have led scholars to question the usefulness of John as a source for evidence of the historical Jesus. The most widely recognized criterion for recognizing historical tradition in John is the overlap with the synoptic tradition. The overlap suggests that John adds nothing to what we learn of Jesus from the synoptics. Scholars generally attribute the Johannine placing to the evangelist’s theological tendencies.

The gospel of John differs greatly from the Synoptics (Mark, Matthew, Luke) and scholars consider it to be mainly unhistorical. The gospel of John is of limited use for the historical Jesus and scholars don’t really use it (Prof. Crossley and Prof. Myles):

Why is John’s Gospel so problematic? Unlike Matthew, Mark or Luke, John presents Jesus as a figure so elevated in the divine hierarchy he is effectively equal to God. John’s exalted view of Jesus as not merely a mortal but a divine man sent down from heaven was controversial and manifests as a conflict in John’s story of Jesus with a generic character/group labeled “the Jews” (or a roughly equivalent translation, “the Judeans,” according to some scholars). According to John 5.18, for instance, “the Jews were seeking all the more to kill him, because he was not only breaking the Sabbath, but was also calling God his own Father, thereby making himself equal to God.” Similarly, according to John 10.33, “the Jews” are said to claim, “It is not for a good work that we are going to stone you, but for blasphemy, because you, though only a human being, are making yourself God.” While many Christians today think of Jesus as equal or equivalent to God, and these ideas are implied through John (e.g., 1.1-18, 20.28), such sentiments are not palpable in Matthew, Mark, or Luke who would not have excluded such controversial material had it been available to them. The obvious conclusion is, on this major theme at least, John reflects a heightened level of theological speculation about Jesus somewhat removed from earlier reflections and is therefore less likely to tell us much about the historical Jesus. Similar conclusions can be drawn from other differences between John and the Synoptics. For example, the phrase “kingdom of God” is common in the Synoptics (Matthew’s Gospel tends to use the equivalent “kingdom of Heaven”) but appears only twice in John’s Gospel where it is no longer used with reference to end times but to being “born again” as a follower of Jesus (John 3.3, 5).

But the contrast does not end there. The Gospels of Matthew and Mark in particular stress the coming of the divine kingdom to earth is imminent whereas the Gospel of John omits all such sayings and replaces them with the idea that Jesus’ “kingdom is not from this world” (John 18.36). Furthermore, the Synoptic Gospels expect the Second Coming of Jesus (a belief that Jesus would return to judge the world after his ascension into heaven) within the lifetime of Jesus’ original audience (see Mark 13; Matt. 24; Luke 21) whereas John 21 explains why this is no longer the case. The obvious explanation is the Gospel of John’s presentation of “eschatology” (that is, the theology of the end-time) reflects a later moment in the development of the tradition where predictions relating to imminent end-time events were not being fulfilled as previously expected and so were being revised accordingly (see also 2 Peter 3). Key differences in John’s chronology of Jesus’ life also point to its complicated use in historical reconstruction. The earliest known narrative account of the immediate cause of Jesus’ death comes from Mark 11.15-18 (and is followed by Matthew and Luke), namely, the account of Jesus overturning the tables of the moneychangers and the seats of the dove-sellers in Jerusalem during the festival of Passover.

> The Gospel of John, on the other hand, places the Temple disturbance near the beginning of the narrative (John 2.13-16) and instead has as the immediate cause of Jesus’ arrest and execution his miraculous resurrection of Lazarus (John 11). When any Gospel author has good theological reasons for including certain material, scholars will quickly raise questions about its historicity. Whatever we make of the reliability of the account of the Temple disturbance in Mark 11.15-18, it is not inherently implausible to the critical historian as an event that could have led to Jesus’ arrest and death. A supernatural explanation like that found in John 11, however, appears more likely a fictional creation than the accounts attested in the Synoptics. Much more could be said about John but collectively these are the sorts of arguments that count strongly against relying on it extensively in the reconstruction of a life of Jesus.

The Fourth Gospel, compared with the Synoptic Gospels, has been viewed as theologically composed rather than historically oriented (W. F. Albright, From the Stone Age to Christianity, 2nd ed. (Baltimore: The John Hopkins Press, 1946), pp. 298-300; C. H. Dodd, Interpreta tion of the Fourth Gospel (Camb. Univ. Press, 1958), Appendix, “Some Considerations upon the historical aspect of the Fourth Gospel,” pp. 444-453; Historical Tradition in the Fourth Gospel (Camb. Univ. Press, 1963); E. C. Hoskyns, The Fourth Gospel, ed. by F. N. Davey (London: Faber & Faber, 1940; 2nd rev. ed., 1947), espec. chs. 4, 7, & 8; A. J. B. Higgins, The Historicity of the Fourth Gospel (Toronto: Ryerson Press, 1960); M. F. Wiles, The Spiritual Gospel (Camb. Univ. Press, 1960), Ch. 3, “Historicity and Symbolism”; Raymond Brown, The Gospel According to John (i-xii), The Anchor Bible (N.Y.: Double day, 1966), ch. III).