Gooseberrybush
You keep stating equivalence between different kinds of things and it is leading you up the garden path of analogies.
Atheism is the belief that there is no god, it has not been proven conclusively, but is a good working assumption for thinking about things that can be observed and thought about rationally. It something similar to the assumption that the laws of physics are uniform, which has prooved itself the most reliable assumption for understanding the known universe to date but of course could be disproved tomorrow (actually, they are the same assumption)
A religion is many things -a belief system with no basis in evidence (like homeopathy) a set of ideas and teachings about the way to live (like socialism) an institution with a business model to keep it going and attracting and retaining adherents (like Walmart) For many people it is an important part of their way of life and identity (like the Justin Bieber fan club).
An ethnic group is a group of people who share a degree of common lineage and elements of culture (with much fuzziness around the edges, there is really no such thing as race) you cannot generally choose your ethnic group.
So atheists don't seek 'respect for their beliefs' anymore than we seek respect for the view that the sun will rise tomorrow.
Atheists can't meaningfully 'respect' explanations for the world that involve bending the laws of physics - gods, ghosts, immortal souls and such like. Of course they can be polite about delusional beliefs when it's called for.
Not respecting beliefs that contradict the laws of physics is not bigotry. It's really hard to be bigoted about the laws of physics.
Athiests can respect purely metaphorical religious practices where people do it because they enjoy it. But this is more like the Justin Bieber fanclub - whatever works for you, just don't inflict it on others or expect extra protection for it beyond normal freedoms. Few religions are able to stick to the purely metaphorical practice, particularly in relation to impressionable young minds.
Atheists don't defend the Chinese gulags, the Stalinist labour camps etc... because atheism isn't a club or institutions.
Saying something considered offensive by people who chose to identify with a religion is not the same as saying something pegorative about all the people who happen to be considered as an ethnic group.