As Tommy says in Goodfellas, “I wonder about you sometimes, Henry. You may fold under questioning.”
The most powerful tool for breaking your assumptions down to principles is to question them. You have to put your own understanding to the test because that is what everyone else will do when they hear or see what you believe.
Much like in a debate, you have to actively seek out the holes in your case that will lead to your defeat. You may fold under questioning, but it’s better to do so when you’re questioning yourself and not when reality itself makes you answer its demands.
At the same time, you don’t have to reply to every question. Some things you must be delusional about and believe in when nobody else does, and that requires a significant amount of self-awareness. Even then, you could find a way to answer many questions about why you have a steadfast belief in what you do. When someone comes bearing concerns and doubts, don’t shoot the messenger—embrace them. You will be better for it even if their questions annoy you in the moment.