I think to an extent, it’s perfectly rational to embrace a certain kind/level or irrationality.
As far as I can see in this flash of thought, largely simply because it allows the psyche to ground itself in certain attitudes/methods which cannot be uprooted by any sort of thoughts, evidence, and arguments. Of course, such irrationality does not serve when exploring an object of interest at odds with irrational belief (i.e., questioning the existence of God as a religious person). But when I think of it from the idea of psychological stability, it certainly helps with that. The strongly religious are much less likely to become disillusioned and mentally ill. I think then this trait of irrational beliefs, that it cannot be torn down by any evidence or argument or theory due to lacking any itself, is most effective when the belief is something that breeds progress and prosperity while directly clashing with as few potential objects of interest as possible. For example, I am currently exploring this with self-love. To say “I love myself” without any rhyme, reason, or condition. Not even a “I love so and so about myself (such as eyes, ability to play, teamwork, etc).” To say I love myself based or dependent on absolutely nothing. I think that creates a constant power within oneself. Since that love isn’t dependent on anything, nothing can influence it. As for potential clashes, I can only imagine it might cause conflict in the process of deep self-reflection if self-love isn’t realized to be irrational and blocks out any self-criticism. Self-reflection is one of the most important steps for human growth and maintenance and therefore it important to note that as I see it, self-love can exist and not hinder self-reflection if one understands that their self-love is irrational, untraceable to any line of logic and reason, and that self-criticism and change is necessary for growth. Self-love does not mean to drown out and forget and go on without addressing one’s flaws, but rather to understand and forgive and constantly try to improve. Love doesn’t mean to forgive and forget. Love means to forgive and never forget, but to improve and move on positively.