Why I don't believe any of them is the same reason I don't believe in fairy tales. It has nothing to do with what other people do or don't believe. Religion is just a form of Little Red Riding Hood that's believed to me.
Actually, the reason you don’t believe in fairy tales is probably because believing in fairy tales gets you socially ostricised. I don’t think anybody here ever ran through the Little Red Riding Hood story to find the indescrepancies. First, it wasn’t taught to you as a fact, and, second, you sure as hell wouldn’t start believing it later due to the social punishment you’d get for it. Yeah, maybe if it was taught to you as a fact and it was considered okay to believe it, you might have later in life worked through it and found it lacking, but
then it’d be analogous to religion and you wouldn’t be able to just outright dismiss it.
When you say “Religion is ridiculous,” you’re just telling us that it’s worthy of ridicule. Maybe that works for less popular but still widespread beliefs (especially if you’re of a higher social class so people have more incentive to be seen agreeing with you), but religion seems to be too popular and entrenched for ridicule to work if you want to get rid of it.