My mother is xian, but my Jewish grandmother begged her to have us kids learn Judaism, even after my parents divorced. So I had both, although after I finally went to Temple and Hebrew school, I much preferred it to the xian cult, and became ever more insistent about Judaism being enough religion on my on time, thanks very much. Bad enough I went to a xian school, but to sit through their hate cult meetings was intolerable to me.
Judaism was a big reason why I became atheist. I connected with it and its community better than I ever had the xian cult, but that wasnt what unsettled me. The shock of realizing not everyone believed the same things had me questioning if either one of them knew what they were talking about.
And then came that day I was doing homework for my parochial school religious class, about the 10 silly rules, and the textbook said that we could have no other deities but HaShem, because HaShem was a jealous god.
For all of my life to that point, every adult had drummed it into our heads that jealousy was a bad thing. And nearly all of them had also told me that HaShem was perfect. But if he was jealous, and jealousy was bad, then he couldnt be perfect. Because jealousy was bad and a perfect being couldnt be bad...right?
And the light bulb came on then and there: All this guy in the sky stuff was bullshit, just like Santa Claus.
I never again believed in the invisible space buddies. Yeah, I went hardcore Judaism for a while in the 90s, but that was a connecting with my heritage thing, not religious. I havent been to Temple in at least 20 years now, and its been even longer since Ive attended a xian ritual. Maybe the 80s, when the USAF tricked us into attending the holy roller service during basic. I got even by spending the rest of Sunday mornings sitting outside and smoking until a service was over. Nobody was ever the wiser for it.