Sure -- that's why I specified religious believer (i.e. someone with faith in their deity/religion, not a religiously-cultural agnostic/atheist). I myself am culturally Jewish, but don't believe in the religion or in any particular deity. But I grew up Orthodox, and for the most part they nearly all actually do believe in a God. It's not fake! And they're not stupid; plenty of them are extremely smart, hold advanced degrees, etc. The OP's belief that since ancient people were smart, they must not have actually believed in gods, just doesn't hold. It's a myopic viewpoint that can be dispelled simply by talking to people today who believe in gods and are perfectly smart too.
I suspect again that it comes from this religious-vs-atheist trench warfare that has developed along mostly political boundaries in the US. On the other side of the Atlantic, I'd claim religion is mostly just a private thing that people don't bother each other about much.
When a large part of the population vote based on their religion then separation of church and state doesn't really work. For example if a part of the population votes that all stores needs to be closed on Sundays because Sundays are holy days then it affects non-believers. That isn't a joke, that is what some countries in Europe looks like, how do you argue against that without arguing that their beliefs are nonsense?
