resident Jewish expert weighing in here.
historically there is evidence of a preacher named Jesus in the Galilee under Roman occupation. His name is mentioned in the contemporaneous writings of a Romanized Jewish chronologer named Josephus. Most of what we know about 1st Century Palestine comes from Josephus' writings. "Jesus" by the way, is the Greek version of the name. if I recall correctly, the Aramaic version (Aramaic being the language spoken in the Galilee in that era) was closer to Yeshua --- Joshua. actually a fairly common name. to deny the existence of Jesus as a man is not logical. to give him status as anything other than an itinerant preacher -- that's theology.
my understanding of Islam is that Jesus is considered a prophet on par with Moses and the other prophets of the Old Testament. only Christians deify Jesus. I'm sure our resident experts will correct me if I misunderstood this part.
as for Jewish theology -- when the Messiah comes, he will rescue and redeem the Jewish people as a whole, not act as a personal savior. in Jewish theology, he will not be "the son of G-d" or have any qualities of godhood. that's where Jewish and Christian theology diverge.
