The reason I am glad that I retained it until my early adulthood is because it did bring me much comfort as a child, and by remaining in the beliefs of my family, it gave us a happy and harmonious household when I was growing up.
I cannot claim that I went through the same intellectual journey as the narrator in the video I linked, but there are definitely some overlapping elements in how we arrived at where we are today. And that is not to say that I self-identify as an atheist today either, I prefer to think of myself as an agnostic, because I lack the conviction of faith to discount the possibility that there might be at least one religion out there that I have not met, that has some founding in truth. My eldest brother identifies as an atheist though - which comes simultaneously as a surprise, but not a deep shock to me. He embraced Christianity far more deeply than I ever did, even aspiring to be a youth minister at one point in his life. He has never spoken to me a lot about how he parted ways with his faith, but he has tossed about terms like "internal inconsistencies" and "fails to stand up to critical examination".
My initial stirrings of doubt came after I had moved out of home, and into an apartment with my elder (not eldest) brother. I became close friends with a guy who had been working his way through our family, befriending my eldest brother first, then moving on to my elder brother when the eldest moved away, and then on to me when that brother drifted off to become closer with some of his more fundamentalist friends. After I moved to another city, he and my younger brother became very close for years before they had a falling out.
This friend and his wife belonged to one of the stranger offshoots of Christianity that had its roots in the 70s (though the church has since moved to being mainstream evangelical after the death of its founder in the 80s, even going so far as to denounce him as a heretic and false prophet).
Many of the his church's tenets were outright loony in my view, and though I avoided teasing him about them too viciously, I was always struck by the mental gymnastics he would have to jump through in order to defend them without making them sound really stupid. I had always found his religion a bit daft because it did not match mine, but it made me a bit uncomfortable with the knowledge that I had to jump through similar hoops to defend mine when some of its sillier elements were brought to my attention.
While that made me question my beliefs at times, it was not the wedge that split me from my faith; it was the people in my faith who drove the first wedge.
I was raised in one of the very fundamentalist religions, where disdain and hatred for those outside of the faith were masked by the ostensible, positive-sounding maxim of "Love the sinner, hate the sin." There was a disturbing level of underlying hypocrisy in the words, because there was no love at all for the sinners. Many members of our faith, and of kindred faiths could barely suppress their glee in the idea that sinners were looking forward to an eternity of damnation and torment after they died. They loved capital punishment (even though we'd not had it in Canada in some years) because it just sped along the process a bit for these awful people to meet their awful afterlife.
And that leads to another wedge; Hell.
I could not resolve myself of the idea of Hell, at least not in the context of a loving god. Our lives are short. The length of an individual life against the entirety of human existence is almost ludicrously short. But when you look at the entirety of human existence against the the time that Earth has existed, it is almost forgettably short as well. When the sun swells to its red giant form and burns our world to a cinder, the length of time between our planet's formation and destruction is immeasurably short compared to the expected lifespan of the universe before its heat death.
Yet when the last sub particle evaporates from existence an inconceivably distant time in the future, and time itself ceases to even be a concept, one's time in Hell would barely even be getting started. Yet the vast majority of people who have ever lived, or ever will live will be condemned to this place of torment and torture. I questioned the competence, and the love of a god who would design a creation in such a way. What loving god would knowingly create a race of beings in his image with the intention of torturing the vast majority of them for all of eternity?
Either he was not very loving, or he was just incompetent, and the result had never occurred to him.
It occurred to me that the concept of purgatory suggested that others had the same misgivings. The idea of infinite punishment for finite sins just did not seem like a concept that would come from a loving, rational being. The current pope has gone one step further, even publicly embracing the concept of universalism during his tenure. I may not agree with him on some of the more fundamental points of his church's dogma, but he scored many points with me when he started espousing that. Of course, that concept does not sit well with people who are holding out hope that Islamic extremists and their ilk have anything but an eternity of torment to look forward to in the afterlife.
Ultimately though, it was neither the hypocrisy, nor the contradictory nature of Hell that drove me to part ways with my religious beliefs, but the realization that God was not a necessary part of my personal equation. The world still worked, whether I believed in him or not. I found that I could love, hate, wonder, fear, feel compassion and do all the things that let me function as a human without feeling like I needed an invisible entity watching every moving and judging me for it. I could judge myself. When I held up a hand and blocked him from my sight, life went on about the same. Ultimately I realized that this god was neither good, nor bad, loving nor wrathful.
He was irrelevant.