Depending on the definition of religion, I could go with AND. If religion involves "faith" or "deity", then I have no use for it. It just sounds like wishful thinking that doesn't really make any sense.

While science may fulfill the same role in one person's life that religion fulfills in another's, calling science a religion is disingenuous. Religion usually involves faith and deity; a person who rejects them should not be called religious, at least not without a lot of qualifiers.