I understand that Hinduism is a very open religion that allows you to understand the world's people's religious experiences and accept them all. However, what you are saying doesn't make sense to me because atheism is, by definition, a disbelief in any deity. If you are a Hindu (or Christian or Muslim etc) you are by definition a theist. As someone above said, you cannot be both fat and skinny at the same time. By the same logic, you cannot be both a theist and an a-theist at the same time. It is logically impossible.
This has nothing to do with social norms or acceptance; it is a logical impossibility.
Now, if you instead say "I believe in many of the teachings of Hinduism including the acceptance of other "religious" dogma but reject the notion of a deity, that's fine. But, that's not Hinduism. That's probably closer to secular humanism with a strong understanding of Hindu doctrine.