Why are the religious so sensitive?

[Tiberius]

If you think it wise for a theist to keep an open mind to the non-existance of God then why is it so silly to think it wise for an atheist to keep an open mind on the existance of God? Some do. They're called agnostics.

Wrong actually, but you admit yourself that you do not have a good knowledge of atheists, so it was very likely that you didn't have a good knowledge of agnosticism either. You are excused for making an honest mistake

An "agnostic" is someone who thinks that something cannot be ever truly known. It is a measure of knowledge, not of belief. I am an agnostic atheist because even though I do not believe in gods, I would never make the statement "I know gods do not exist". An agnostic theist likewise admits that they could never say "I know god exists", but they still believe that such a god exists.

Knowledge is a subset of belief, not the other way around. It is possible to believe in something (or disbelieve it) without having knowledge of it.

Gnostic atheists and gnostic theists are the opposite. They claim to know about the existence of gods, definitively.

Agnosticism as a synonym for "not sure" is a very recent misconception. Apatheism would best suit people who really "aren't sure".

I can't say for certain, but I reckon most of this forum are probably agnostic atheists. They far outnumber the gnostic kind.