The rational stance in life requires direct observation before belief is granted. It's "I'm from Missouri - show me." It's "Prove it, big fella."
Yet none of us is really able to do this, because there is just too much going on. We don't have the opportunity to investigate everything for ourselves, so we have no choice but to rely on "experts" as the source for many of our opinions and beliefs. There's just no escaping it.
For example, the champions of evolution never personally observed a fish crawl out of the water and start breathing the air, but experts assure us that this did actually happen. We have no direct experience to confirm the idea, and very few people have reviewed the scientific literature that supports it in order to make their own informed assessment - yet a rational, scientific person will tell you that it must be true. It's the faith of people who believe the guy in the white coat rather than the guy with the white collar.