I wasn't indoctrinated into a religion, so when I did hear of it it sounded really stupid.
Nothing since has swayed that initial assessment.

My grandfather was a nazarene minister and screamed his hellfire and damnation sermons which, as a very young child, made me terrified of god. my grandmother, his daughter, was gentle, loving, kind and nurturing--really, what you expect good christians to be like and so I wanted to be like her and avoid the hell he screamed about. I NEVER accepted that god could be truly good and all powerful if he let innocents suffer and die and I could never get a straight answer from anyone in the church except for the 'god's plan' and 'mysterious ways' bs. then I had children and worked in a child abuse triage center. days old infants to teens, raped, tortured, starved, beaten, burned, sold and their bones and skulls fractured beyond recovery convinced me that the god I read about in the bible could not possibly exist and allow such suffering...

Just more and more things didn't add up and religion had zero answers, or rather, the answers they had were insufficeint and plain dumb many times.

I questioned religion when I asked the adults in my life what came first, cave people or Adam & Eve and was told to stop asking questions like that. I thought it was a simple question even as a child I realized the time was a straight line. If anyone in my life would have had any imagination, they would have said that Adam and Eve were the first cave people. I would have accepted that answer.

The God I was told about as a child (He's got the whole world in his hands right?) did not match the God in the book they gave me later on in childhood, which I had both the tenacity and audacity to actually read at 9.
And the river of pointed questions began to flow . . .
By age 10 the Reverend came to our Homa and asked my mother to keep me from Sunday School, as "He is a seeker and will therefore find" but dines on Steak where the other children are on Milk and his questions confuse them.
Actually I pissed off the teachers and the Reverend, because they had no good answers and I called them on that at 10, the last one being bringing up the 200 foreskin Dowry of my namesake, and how could that be good? Why would a good and loving God see that as good?

So I distrusted religion, but the God idea itself would take another 15 or so years to fully be free of, so deeply had society and religion indoctrianted my childhood mind.

I would have to say when I learned more about science and found it didn't jibe with religion. I was a science major in university. So my religious friends might say university corrupted me. lol.

Now that is a really good question. I never got religion, so that was never a thing. Thinking? I guess I have always been an over thinker. But I have been embracing the not over thinking thing for the last couple of years. You know that principle of saying "yes" to everything and anything? That has been me. Generally good, with a few exceptions, but I'm not sorry.

I'm sorry religion was such a trial for you. I find it bitterly amusing that this thing - faith - which is supposed to sustain you turns out to be an absolute pisser. I don't know what happens next. Despite the pretenders (and I'm not talking about the band The Pretenders, because they are awesome) no one knows. Make the most of what you've got.

When science began to make more sense than religion.

Birth. Been doing it ever since.
Can't seem to stop it.

Where were you before you were born?..no where right?..well thats what death is..or have you ever had surgery and had general anethestesia?..where did you go?..same place..no where..

Regrettably I was wholly credulous about the fundamentalist BS well into adulthood. My attitude was, I'll conform to anything that promises me approval, comfort and safety, from god or man.

What got me doubting was the fact that my religious faith did nothing to accurately explain or predict experienced reality. It was full of unpleasant surprises. People I loved and cared about sickened and died. My first wife succumbed to severe mental illness, my second to a rare neuroimmune disease. My mother died in a car accident. One of my brothers, a very devout and good man, died of a rare bone cancer unrelated to his lifestyle. Things just simply didn't go as they were "supposed" to. By the time all that had played out, I was no longer the Biblical ideal "husband of one wife", and had a bunch of very serious questions about how reality actually works.

Once I started questioning my faith, I realized my own role in it -- I was a pleaser with a huge Jesus complex. And then over a period of years I began to change my views on reality, developed a much more accurate mental model, and my life became far more comprehensible.

My adult son died a couple of years ago, which was my first such loss as a full-on and, I hope, relatively mature unbeliever. I found that loss no less painful in its essence, but I also found it a huge advanatage not to have even residual religious questions in the mix. Those useless "why" questions -- why him, why now, why is god punishing / ignoring / testing / hiding like this, etc etc. No more dark nights of the soul beyond what the viccisitudes of life bestow on their own. Life is just stuff happening, it is not personal, and it does not owe me anything. Being free of the entitled notions I was suckled on, has been a gigantic improvement in my quality of life.