Changes in belief are not the result of brute force, but of expanded understanding.
You can’t coerce yourself into believing something that is inconsistent with your perception of reality.
Belief is an involuntary psychological response to your conceptual framework.
Feeling guilty for not believing what you think you ought to believe isn’t the same as actually believing it.
Whatever you believe is precisely what you must believe given the overall combination of elements that constitute your worldview.
Your potential for self-reinvention is located within your ability to tinker with those elements.
If you want new beliefs, explore new experiences; find new facts; visit new places; engage new people; contemplate new philosophies.