Why do some atheists lose their head when you suggest that Jesus did not exist?

A little background, I saw a discussion of if Jesus had a wife on another forum. I wrote that we cannot be sure enough of even the existence of Jesus to meaningfully discuss it. Suddenly a bunch of people started going nuts about me even suggesting it including a number of non believer.

Now, I honestly don't know if there was a historic basis of Jesus. I have read both sides and do not consider either side to have made a strong enough case to make a decision. The thing is that I have given some effort to learn about the issue as well.

So why do you think some atheists lose their head when you suggest the idea?