The most "authoritative" accounts of a historical Jesus come from the four canonical Gospels of the Bible. Note that these Gospels did not come into the Bible as original and authoritative from the authors themselves, but rather from the influence of early church fathers, especially the most influential of them all: Irenaeus of Lyon who lived in the middle of the second century. Many heretical gospels existed by that time, but Irenaeus considered only some of them for mystical reasons. He claimed only four in number; according to Romer, "like the four zones of the world, the four winds, the four divisions of man's estate, and the four forms of the first living creatures-- the lion of Mark, the calf of Luke, the man of Matthew, the eagle of John (see Against the Heresies). The four gospels then became Church cannon for the orthodox faith. Most of the other claimed gospel writings were burned, destroyed, or lost." [Romer]
Elaine Pagels writes: "Although the gospels of the New Testament-- like those discovered at Nag Hammadi-- are attributed to Jesus' followers, no one knows who actually wrote any of them." [Pagels, 1995]
Not only do we not know who wrote them, consider that none of the Gospels existed during the alleged life of Jesus, nor do the unknown authors make the claim to have met an earthly Jesus. Add to this that none of the original gospel manuscripts exist; we only have copies of copies.
The consensus of many biblical historians put the dating of the earliest Gospel, that of Mark, at sometime after 70 C.E., and the last Gospel, John after 90 C.E. [Pagels, 1995; Helms]. This would make it some 40 years after the alleged crucifixion of Jesus that we have any Gospel writings that mention him! Elaine Pagels writes that "the first Christian gospel was probably written during the last year of the war, or the year it ended. Where it was written and by whom we do not know; the work is anonymous, although tradition attributes it to Mark..." [Pagels, 1995]