Belief systems carry a lot of power in your human experience. They are the foundation from which you operate. Much of that foundation was laid before you were verbal. It is created from beliefs expressed and lived by your family of origin, the citizens of your country, the people from your faith tradition, and other caretakers, schools and institutions that were a part of your life. It is a jigsaw puzzle of actions you saw, foods you tasted, emotions you felt, thoughts you had and strong statements you heard. These all went into you from the beginning and at various developmental stages to create the belief system you have. Your actions come from the thoughts that are generated from those beliefs.
If you are willing to do the work, each experience offers the chance to go deeper into your understanding of your belief systems. There can be a bunch of dark stuff down in there that you have no idea exists because so much of it is at the subconscious level. It takes time, patience and a willingness to really see yourself as you truly are. If you are willing to bring light to those dark places, you will grow by leaps and bounds.
Letting go of those old false beliefs will set you free.