As you were born and enter whichever culture and age you were born into, you start of not knowing. Yet your survival depends on adapting to and being accepted by your caretakers. The best way to relate to them (the only obvious solution to the problem...) is to melt into and take on their assumptions, expectations, explanations, language, habits, style, and yes, their Beliefs.
You simply start copying the script as you encounter it as a way to interact with the world.
The result is that much of what you hold as 'an accurate and appropriate interpretation of the world' is believed to be true, but may not be. Without having the power to choose about it you end up absorbing Standard Human Intelligence Thoughtware (S.H.I.T.) which in the modern world in thoughtware from a capitalist patriarchal empire.
As a baby and up through childhood, the strategy of being a chameleon with your surroundings works well. As you reach 18 years old, this may no longer be true.
By approximately 18 years of age, you have built (often by 'accident' and with the help of 'coincidence'... which is E.C.C.O. at work...) enough Matrix to hold the Consciousness (which shows up as Responsibility - because Responsibility is applied Consciousness... Consciousness in action...) to be Responsible for starting over at zero and making your own choices about what is true, what is useful, and what is the best way to live in the world.
What this means is that, if you experience in yourself the application of any Belief, either in yourself or in others, what you are experiencing is the Child Ego State in action, which is a desperate move to resort to childhood survival strategies.
Effectively taking Radical Responsibility for Belief in yourself involves very different approaches than effectively taking Radical Responsibility for Belief in another person, a group of people that you are a member of (such as a department in a company, or a family),