How is it that people are able to wear crosses, hijab's, religious t-shirts to work? If I wore my religion (atheist) if likely get written up?

Yes, it is a double standard. If your workplace allows one of them, they should allow all of them. The easiest solution would be for your workplace to ban all religious (or atheist) symbols, which would also be fair.

There's a different in expressing someone's religious beliefs and wearing a shirt to **** people off. I don't need to wear an atheist shirt nor would I buy one. I also don't get offended if people wear a cross or religious shirt to work.

There was a news story I read awhile ago. When a kid wore a gay pride shirt to school the next day a group of students wore the Confederate Flag to school. The later claimed since the kid could wear a gay pride shirt they should be able to wear the Stars and Bars.

You have the free choice not to wear any of those things.

Why does it matter to you that others make a statement?

"Coexist" is nice in theory, but, as you say, loses by exclusion and not inclusion.

The religions are using all of their magic and spiritualism to defeat you.

I guess, when they say "choice of religions", they mean "choice of religions".

Atheism nor theism are religions. Religions are subsets and may be theistic (Christianity) or atheistic (Buddhism.) Take your trolling elsewhere.

Yes, so stop whining