I respectfully disagree.
While rationality is not the basis/source of our beliefs, that doesn't automatically place them into the "against" reason/rational reality position.
Even if we take your angle on this, if you were a kid who got beat up hundreds of times when you walked down alley ways by one or both 6-4 white blond weightlifting twins...and when you grew up you acted in an "anethema" way toward tall blond men, weightlifters, or blond male twins, or walking in alley ways, such a perceived "phobia" wouldn't be "irrational." It'd be based upon a pattern of real-life experiences. The kid-now-adult simply has a "faith" that certain characteristics in people or cities are not good for his health. Frankly, his reaction is very "rational" if the threat was still real AND if he wanted to stay alive and well.
Faith is not always aligned with what some would deem "rationality," but that doesn't make it inherently "irrational."
Christians, including Mormons, believe in the divinity of Christ, the Virgin Birth, his resurrection, and salvation through his atonement. Those are supernatural, not “rational,” matters that defy understanding through any means other than faith.