Why do atheists get so nervous when they are asked some difficult questions?

Take your best shot. Ask your "difficult questions."

But I will tell you what is frustrating. Christians ask the same stupid and discredited questions repeatedly as if they had some great (excuse the phrase), "revelation". It can be frustrating to have to point out circular reasoning, the arguments of ignorance or the misrepresentation of what the atheistic position is, which Christians use so frequently. It is not deep or intelligent to make the same boring arguments and the only thing that is "difficult" is having to repeat the same explanations when the original publication ignores them.

I mean seriously, how many times do we have to give an answer to the Cosmological Argument, Pascal's Bet or my favorite (you can not explain X, so it must be God)? Bring something new or interesting to the table or you're just wasting everyone's time.