Finally, it is worth pointing out that the NT as we have it, and especially the gospels, is entirely dependent on that branch of Jesus’ disciples, gathered around Peter (and Paul), which is centered on the kerygma of the resurrection. Acts has preserved a few traces of other groups: Apollos and the disciples at Ephesus, who know only the baptism of John, represent at least one other current, which must have lived on with its own teaching; a similar observation could be made on the subject of James, to whom even Peter gives an account of himself. Little is known about the Jewish-Christians, but their biography of Jesus (the “Gospel of the Hebrews”), which was apparently not published, would have presented a rather different picture from the one we know, even if the facts related were more or less the same. Traces there certainly are in the NT, but they have been almost obliterated by a final redaction which has a different orientation. Similar traces are to be found also in the Eastern Churches, which regard themselves as the heirs of Jude, Thomas, etc., although nothing in the NT would lead us to suspect that. . . . .
. . . .
From what has been seen in the previous section, it is clear that the gospels are not the best place to look for the origins of Christianity, that is to say, for what happened immediately after Jesus left the scene.
Nodet, Étienne, and Justin Taylor. 1998. The Origins of Christianity: An Exploration. Collegeville, Minn: Liturgical Press. (pp. 38, 39)
Nodet and Taylor cite two reasons for that conclusion: 1, the long delay from the time of Jesus until the “publishing” of the gospels; 2, “the almost total silence regarding rites.”
Now the NT, by and large, gives no information about how to perform any rites, despite numerous allusions to them. Even more: in the gospels Jesus institutes nothing.115 In other words, many things to be observed remained unpublished. (p. 39)