I was mormon up until around 30ish. However, researching the history of the mormon religion ultimately led me to completely disbelieve the faith claims of the church.
From there, atheism was just sort of natural. Why, for example, would I suddenly believe that any other religious sect got it's supernatural claims correct when the one I was raised with, got a bunch of the "good feelings" from and was 1000% convinced was true ended up having really major issues?
I certainly could be convinced there is a god, but it cannot be through emotions. My emotions held me in mormonism for far to long. I know emotions can trick, deceive, and are easily played to. The right type of music or a charismatic orator can easily trigger them.
So what does that leave me with? Facts, logic, and evidence. Any religion that can give me solid evidence that the supernatural is real and exists would win me. None have succeeded (and I have had fun looking into a few).
If there is an all knowing, loving god that cares about me, then that god would know exactly how to present me the evidence I need to believe in it. If that god doesn't care about me, then why should I care about it?
And, if there's a supernatural belief without a god that I should believe in for afterlife rewards... well, there's just no way for me to correctly stumble into it. I need evidence that I'll be reincarnated as a spider if I don't believe in reincarnation, and that seems pretty tough to prove.