Answering questions like this is very probably what got me blocked by Jeremy M. Thompson, but oh well.
The Internet, and Quora by extension, is dominated by atheists. My theory is that many atheists consider the Internet to be their home, not the real world. Reason being they feel alienated by their home lives and communities, which in most places with the Internet back in the nineties when it was really kicking off, was dominated by Christians and their oft-judgmental ways.
So long before the Christians found the Internet, atheists had already virtually colonized the place. I’ve seen many, many, many social communities where the few religious voices were overwhelmingly chased away by atheist torches and pitchforks. Atheists didn’t lose their tribal predilections when they lost their religion.
The religious people I’ve known in the real world, when they do participate in online communities, tend to stick to the few enclaves where they feel welcomed. They also spend a lot less time online. Whereas just about every atheist I’ve ever known has spent vast quantities of their time online.
I’d be willing to bet that, among people with strong feelings about the God hypothesis, atheists outnumber theists on Quora 10 to 1.