Regarding belief, I think there are two strategies we can pursue: being open-minded and being close-minded. Sometimes people get moralistic about this, but there is no need to be. Being close-minded is a a strategy that has a lot of advantages. Being close-minded means you are unwilling to subject some of your beliefs to revision. Revising beliefs takes energy and it can provoke anxiety. Also if you are open-minded it can make you less reliable — you could have made a promise to another person or to other members of a community based on certain beliefs, and if you are open-minded you are more likely to break your promise.
The chief drawback of being close-minded is that it doesn’t make it possible for you to adjust your beliefs to changing circumstances. Your set of beliefs worked for you or for your ancestors, but the world changes, and we gain new information. If you are unwilling to revise your beliefs you can get stuck in a sub-optimal pattern of coping with the world, which may ultimately prove fatal, or otherwise drastically impoverish your life and its possibilities.
But being open-minded has its drawbacks. The chief one is that if your mind is open, and you have an internet connection, other people and entities with try to blast garbage into it. This may be well-meaning garbage, or it may be actively evil, in the sense that it has no concern for your own flourishing but is just intended to advance the interests of someone else –a cult, an advertiser, or a political system.
I think philosophy is a life-skill for being open-minded while maintaining one’s balance. It you compare a person to a cell, philosophy is like the selectively permeable membrane. If you compare a person to a body, philosophy is something like the immune system.
Of course we don’t have to make a sweeping decision to be open-minded or close-minded. We can be open-minded in certain contexts and close-minded in others, and we can have some members of our society specialize in being open-minded and others specialize in being close-minded, taking advantage of the natural distribution of temperaments between those who are open to new stimuli and those who are adverse to new stimuli. But if we are going to do that we will at least have to be open-minded on the question of whether to be open-minded or close-minded, and that requires philosophy too.