While some believe there is no historical reason for believing that Jesus of Nazareth exists, I believe that his historicity is irrelevant to my rejecting him as the promised Messiah that my people, the Jews, have been waiting for.
A good man? Likely? A rabbi who gained a following and someone who might have even performed miracles. Even if he resurrected as Christians believe, the fact that Jesus didn't operate in the open like Moses did, did not want his miracles to be widely known in contrast to the way Moses performed his wonders so that all could see, and that Jesus did not lead his people into the Promised Messianic Age as Moses led his people to the Promised Land are just some of the reasons I don't believe he is the Messiah.
The fact that Biblical scholars from Catholic and Protestant circles are now in agreement that an anti-Jewish polemic tainted much of the New Testament writings with the intent to compete with traditional Judaism for recognition by Rome and legitimacy in the eyes of potential converts is another reason that I keep my stand. This polemic in Christian Scripture has traditionally been interpreted as historical over the past 2000 years to the detriment of the Jews and much of the rest of the world that did not agree with the movement.
Christians now offer apologies for their actions and inactions during the Spanish Inquisition, the Crusades, the pogroms, and the part they played in the Holocaust revealing a legacy of repeatedly being on the wrong side of history again and again. Today there are many of them that currently persecute and oppose the LGBT community, some demonize women who side with pro-choice political movements, others insult law-abiding Muslims by holding events to draw cartoons of Muhammad, and many go about viewing Jews as blind, lost and in need of proselytizing to the teachings of Jesus lest they end up in Hell for remaining Jews.
I see another 2000 years of apologizing for being on the wrong side of history by Christians the way they are going. Such does not make a Messianic Age nor composes anything hoped by the Jews from antiquity. We did not hope for 2000 years of violent persecution, hatred, bigotry, and genocide but that is what the world got with Jesus.
So again, let Jesus be as real as you me. It matters not what the final truth is on that. Do I believe he was the Messiah? No.