I was brought up in a Christian household, as are most in my country(Greece), but do not imagine anything 'extreme'...in fact neither my parents nor I really went to church unless it was Christmas or Easter
So I became an atheist since first year of highschool, I think...no great (de)conversion, just a realization that there is too much *meaningless* sufferring in the world, without any purpose or goal(for example, a 1yrold infant dying of brain cancer, which has happened to a family I know). Plus, even if I was willing to believe in a personified, benovelent deity, I have absolutely no way to choose which of the versions of it is actually the right one, since there are virtually no solid evidence, just groups of people which believe, with the same conviction, that their version, most probably passed on by their fathers, grandfathers and so on, is the "true" one. Christianity's Trinity? Judaism's Yawheh? Islam's Allah?(just to name the main 3 monotheistic ones). Those are *not* the "same God", they do deal with a God-Creator of the universe, but they describe quite different properties, plus Christians believe that Jesus of Nazareth was God, a notion that is absurd and blasphemous in the other 2 religions.
Then, about 2 years ago, out of pretty much nowhere, I've had an avalanche of religious experiences, a sort of perceived "communication" with God, not in audible or visible hallucinations, but more like a belief I was suddenly "endowed" with a gift to interpret physical "signs" that pointed to the existence of God(the Christian God, to be exact, something not so weird since I was brought up from day 1 in a country/environment where "God" means "Christian God".) I even participated or started some threads here about religion, where I fiercely argued from a Christian point of view, though it was a pov I had constructed on my own, not really relevant to any mainstream dogma(for example I argued that love, not "faith" nor "good deeds", is the ticket to heaven; a loving person is accepted by Jesus into the Kingdom of God, regardless of being christian of any denomination, muslim, jew, buddhist, hinduist, atheist or anything else).
Well, anyway, the whole thing turned out to be , you guessed it, a kind of psychotic episode, triggered by my "genius" decision to suddenly stop taking the anti-depressants which my doctor, who I was seeing for years, and still do, had prescribed, and that treated my OCD and depression. Looking back, it was kind of an interesting period, as I was constantly in a sort of "feverish"/ecstatic state, terribly excited that profound "secrets" had been given to me, though the exact nature of those "secrets" I wasn't really able to define . When the whole "high" eventually faded out, I was kind of embarassed about things I've said(mostly online, as people in real life hadn't really noticed anything significantly different, I kept things to myself), but I decided not to be too hard on myself, and that my brain, going over a sudden chemical "withdrawal" over my idiotic decision to stop taking my meds overnight(note: Do NOT do this!), just...took a wrong turn somewhere. So I'm back to my atheist mode...and that's the end of it.