I guess it would depend on where you live. If you're in the US, England or any other progressive country there isn't any reason you wouldn't be able to join your local freethinker groups. You're certainly very welcome here. I've only known one Arab atheist and most people will never meet one so you guys are pretty rare; I'll hope to see more Arabs walking away from the enslavement of religion.
You may want to start by forming a group here on A/N of arab atheists, or arab-friendly atheists. I'd be more than happy to do my bit - I was a middle east major in college and now have a few muslim friends (all women of course haha)
i live in the worst and the best spot you would ever be in...
west-bank (palestinian terretory)
the worst: because religous terrorism is everywhere from both sides muslims fundamentalists and jewish fundament. despite now it's much less than let's say 4 years ago.....
the best: because i'm in west-bank not in gaza... and here is a great difference, there's somehow peace, i mean our government after death of Arafat became more open-minded, now one can easily go out to the street and say "i hate Abbas or i don't believe in god." so, there's alot of freedom here especially in universities we are unlike any other arabic country.
I'm an arab atheist...born in Egypt and grew up in Canada. I support and hope all arabs would be atheists. I think the addition of rationality to our richly cultured lives would make for a wonderful new way of life for the region and the world in general.