In my case wasn’t a continuous journal probably started at 12 after reading Frank Hubert Dune, I realize that religions could be used to control people. That’s not cause I’ve was brilliant, it’s well explained and almost explicit on the book.
Some time later some of my school mates started to go to First Communion courses and I prefer to not take it.
Later tried to join to a boy scout group near my home and was requested to take the First Communion in order to let me join.
At that point I’ve started to have a bad understanding about Catholic church, but far away for understanding myself as an atheist.
Many years later I’ve read a novel (Couldn’t remember the name) where the principal was the soul of an Egyptian person and describes the travel and stages for a dead man from Egyptian religion perspective.
That intrigues me, so I’ve started to read, first the Egiptan’s dead book, the Bhagavad-guitá (was given as a gift from a monk in a park before talking a couple of days), The Bible, and any other religious book that comes to my hands.
From that I understand that those sacred books are no more than a compilations of the understandings and preconceptions from the people who wrote them, no god involved at all.
But specially reading the bible I understand that that book has nothing to do with the loving caregiver described by the priests and it’s obviously fake and manipulated, or, if god exists and that book tells the true its an abominable monster with heavy personality problems.
So actually reading the bible was the kickoff for understand myself as an non-believer.