A man builds. A parasite asks 'Where is my share?'
A man creates. A parasite says, 'What will the neighbors think?'
A man invents. A parasite says, 'Watch out, or you might tread on the toes of God... '
^ integral non-dualist, very interesting. I would call myself integral and advaita vedanta [which in english basically means/translates as nondualism]
Anyways, sure they can! I view Ken Wilber as atheist [and enlightened] and he uses the word spirit quite frequently in his writings. I think a lot of the answer depends on what one means by theist. I think many people try to avoid it, but an extremely strong case can be made that Buddhism is atheistic. By extension, other religions that hold the same ultimate viewpoint would be as well.
I think of theism as " an external ultimate independent creator god stood outside of creation and made creation, and said creater god is not us/ we are not said creator god." Under such definition Buddhism is absolutely atheistic, as would be Hinduism as well, for example. I think we could define theism in such a way that Buddhism, and others like it, then became theistic. So, like I said earlier, a lot of the answer comes down to "what does theism mean?"
Personally, I've viewed myself as atheist polytheist before, but then I decided there were better words available and that it didn't matter.
Non-theistic would probably be a better term for many Eastern religions, since very often there is a concept of "god" in the basic sense comparable to a first cause or ground of being - just not in the same way as seen in Abrahamic faiths. Furthermore there's no uniform agreement on the status of gods or divine beings in them. I made this point in another thread, especially concerning the difference between the Theravada and Mahayana traditions within Buddhism. Dr. B. Alan Wallace's point is very interesting too, about how deep down there's very little difference between Vajrayana Buddhism and a NeoPlatonic interpretation of Christianity.
Hinduism is a slightly different story, since there's so many different variations of it. There are more than plenty of gods and goddesses, so atheism wouldn't be an accurate descriptor here(atheism meaning without god(s) ); except in the case of the Cārvāka school, which does advance an atheistic perspective.