CalebInFlorida-In the end, once denial is chosen there is no more dissonance as denial is a solution which brings relief.
Yes, but an effort to avoid cognitive dissonance drives that denial decision. At some tacit level, the mental stress becomes unbearable and forces them to shut down, and go into that denial. A person not experiencing such pain would much more readily accept the dis-confirming information and simply adjust their thinking. The problem is, in order to do that, the whole belief system needs to go with it, and that they won't do. Very deep, (and usually existential), fears force the decision of maintaining belief and going into denial, once the cognitive dissonance brings that mental stress to their attention.
Cognitive dissonance is deeply ingrained in human evolution. Animals flee potential danger, even if a more rational view of the potential threat meant that not running away would be safe. Animals don't reason, they react. This helps ensure survival of the species. Humans have evolved a conscience, that allows them to make rational and/or moral decisions when the evidence calls for it. When that evidence presents itself, (such as a person's religious views as being false), a strong, (however tacit), fear is usually experienced. This happens precisely because the new evidence is recognized as likely valid, and poses a threat to their beliefs. This is cognitive dissonance, and represents a mentally unstable state for a person to remain in. The fear is usually too powerful for them to overcome, so as such they go into shutdown/denial mode.
The mental gymnastics described in the OP is what people will go through to justify their shortsighted decision to forego the cognitive dissonance, and investigate further. This causes long-term mental health effects in of itself, as has been pointed out.
d4g