"Because the prophecy says so!"
An atheist Gentleman: "Even though I don't believe in god, I understand that your ancestors have prophesied about a Messiah that is to come. I understand that Christians believe in a Messiah claiming that it already has fulfilled the prophecy. Did your prophets also prophesied about warning against someone like Jesus?"
Christian Gentleman: "I don't think god will twist his prophecy to confuse his people. It is always intentional and straightforward." Because Jews don't believe in their own prophecy, we are believing on their behalf that which also had been prophesied as well."
Urban Dictionary: "Stop arguing!! Prophecy of 'Messiah' refers to:
A. Someone who is to come
B. Who knows.
D. John Doe
E. ___________ (ehh...you fill in the blank. Just give me your email address. Remember, it's public, address only first names, and no advertising.