I'm not sure it is quite as black-and-white as that. I would agree that it is intellectually dishonest to dismiss evidence just because you don't like what it leads to, but human psychology is such that unless we have some very specific education and strategies in place, we are all susceptible to logical fallacies and manipulation. In order to break free from that, we need to be educated in critical thinking skills, how to spot logical fallacies, and the mechanisms used by manipulators. Sadly, once the manipulation has started, it becomes increasingly difficult for the victim to think rationally - and religious manipulation often starts in childhood. IMHO, critical thinking skills should be a core subject in schools - from primary school level up.
Even when we know about cognitive dissonance though, we are still susceptible to it, and we have to implement strategies to negate the effects of bias. I'd recommend Daniel Kahneman's "Thinking, Fast and Slow" for more insights on that (the author acknowledges that psychologists find themselves falling for the same fallacies that everyone else falls for, even though they are aware of them).