Early on I developed some very serious ideas about religion. On some of those ideas I had to grow much older to learn how to express them without contention. On other thoughts I never have learned a way.
One of the things that made a problem for me was an idea held by a Catholic boy who lived next door in Warner Robins. He was fearful that if he even touched my Sunday School book he would have to spend time in purgatory atoning for the sin. I knew a religion where I was supposedly saved from my sin, but where I might yet have to pay for my sin was a problem for someone as flawed as me.
Another problem was one held by some in Christendom, but the few other religions I had been exposed to as a youth also held. That was, you could not know your future state till you arrived in eternity. To me that seemed out of step with a method of salvation one was supposed to believe in, or a Savior one was supposed to freely follow. It was out of step with being utterly saved: "Wherefore He is able also to save them to the uttermost that come unto God by Him, seeing He ever liveth to make intercession for them." Hebrews 7:25
The more I studied on the matter the more convinced I became that the true religion would have to be a know so religion with uncertainty taken out. Otherwise God would be limited in either what He could or would do for me. And that was not to the uttermost. So true religion had to have certainty.