Most people born into the human race are indoctrinated from an early age into the religion of their parents. For the most part this is the case across all cultures and across all religions. A great number of people continue in the "family" religion while a growing number of people look elsewhere for answers. Remarkably however, the vast majority of people when asked will answer with a variant of having arrived at their beliefs after careful deliberation.
As a non believer, I would assume that the way I arrived at what I believe is common amongst people of like mind. At a young age I was in a school system that had the express purpose of bible lobotomizing all children within its grasp by the time they were twelve. Somewhere around that age, I began asking difficult questions, that were never adequately answered (What did the carnivores eat on the Ark?). The hypocrisies, inconsistencies and outright whoppers continually perpetrated by the religious folks around me gave me a push in the opposite direction. After years of study, deliberation and careful consideration of the facts, I've come to the conclusion that most of what comes from the mouths of our species concerning their imaginary God is nothing more than a collective form of wishful thinking.
When I am asked: How did you arrive at your beliefs? . . . I am at a point in life where I can answer honestly: through education and maturity.
How about you?
open mindedly looking at things. All I have to say really