Even though only 190 or so users voted so far, 63% of present people voted either agnostic or atheist. Which is well in line with what I guessed before hand.
I find it interesting that OP did not include "jewish" as an option given how its far more common in the west than say - hinduism. Sikhism likewise is getting more and more exposure.
EDIT: Wow! Just looked at the poll results so far. Lots of people consider atheism their choice of religion.
Atheism is not a religion (and that includes pastafarianism, feminism and other secular "hobbies") in and of itself.
“When men choose not to believe in God, they do not thereafter believe in nothing, they then become capable of believing in anything.”
― G.K. Chesterton
So it could rather be described as form of spiritual diletantism and absence of firm code of conduct.
True lack of belief - nihilism is altogether different. Smart nihilists enter politics, dumb ones kill themselves early.