Proof?

If anything, Atheists are more 'moral' than the rest of society as we have the lowest crime rates of all 'religious' groups, though that probably has more to do with atheists tending to be more educated and wealthy, which are better predictions of likelihood to commit crime.

You shouldn't forget about white collar (tax fraud etc.).

Absolutely true, and thats not to mention that atheists tend to be more liberal, so they support things like gay marriage, women's rights, healthcare for poor, and so forth.  You can argue that these aren't teh correct morals to have, but they are morals nonetheless.

I think Western atheist morality owes its origins to Greco-Roman philosophy instead of Middle Eastern, Abrahamic religions.

Like I said in another post, Chrisitanity borrowed several ethical principles from the Greek philosophers.

True while many are morals can come from either the need to survive or as sapphi_snake said 'Greek philosophers' it is religious that spread these morals and religion that put them down in writing for generations to follow. 

Take examples from differing faiths. Older faiths would regularly do sacrifices both human and animal, while in our western society which is based on mostly old testament laws and morals we would see these as morally bad, in those faiths at those times, a sacrifice may not have been as seen as bad but something to 'please the gods'. It is the faiths and religions that are defining what is moral.

It is recently when atheism has taken hold that many of those morals, like sacrifice was seen by newer/old testament faiths and others as more barbaric and immoral, that what the faiths see as immoral just aren't anymore as defined by understanding.

the fact they comitted a crime and they are in prison

if there were good moral examples of atheists to hold up then people wouldnt assume they are amoral.

just a fiiiiiiine example of arrogance that is so incredibly high among atheists

It all comes down to where you think ethics come from...

I've studied this to a large degree, in conclusion it stems from a desire/need to preserve ones self and the human species. The things that do less harm and brings more happiness are considered the most ethical and moral

No need for religion to tell people what is and isn't moral. in fact, religion makes people do morally questionable acts, such as killing people for various reasons... I recently found out that in Islam, IF that dude who is burning the Qur'ans was in a muslim country, the rule in islam is for him to be KILLED, as stated by the Qur'an/Prophet, same goes for people who talk bad about the prophet and God - death

so no, I don't think atheists are immoral, quite the opposite in fact in my opinion