I'm not sure it's that simple. As Mr Graham points out, we are shaped by our echo chambers, the chorus of voices that shout out against our fellow "heretics". As children, those chambers come from our families and religious / community institutions, as dictated by our elders. As we reach our rebellious phases, sure - we scrabble around and find beliefs we want to believe in - but the effort expended in doing so is difficult and the reward is little. From a social perspective, a little deviation acts as a differentiator - we are made interesting within our peer groups by our rebellions - but too much heresy makes us "other". As we get past that, self-realisation comes in waves; nestled between desires of belonging in a new group, we find moments where we are invited to re-evaluate some deeply held truth. Rarely is the re-evaluation self-driven, and almost never is that belief so different that a nearby echo chamber is not crouching nearby, waiting to nurture our newfound "chosen" belief in it's warm, corroborating belly.
For the record, I want to believe your belief. I recognise that this autonomous self-truthing could be the pinnicle of what we as humans could become. I also think the very concept of society becomes a meaningless nothing if it were possible.