Denial of evidence and reason Some people form a belief and become absolutely resistant to any contrary evidence or reasoning. Even in the face of overwhelming evidence, these people stick to their beliefs. I'm pretty sure this is something that has been investigated by cognitive sciences, and I'd like to know what this phenomenon is called as I'd like to learn more about it.

So, what is the mechanism of this denial-of-evidence called?

I recently came to the conclusion that a lot of people who hold onto conspiracies and the like show similar behaviors to religious fanatics. The way these conspiracy-believers argue and the way they react when confronted with critique or even evidence seems to be similar, no matter what conspiracy-topic it's about (with varying degrees of fanaticism, of course; some can still be reached with reason while others are so deep into their belief-system that they cannot be reached any longer). I find this strangely fascinating and would like to understand the "mechanics" of this phenomenon.
Confirmation bias:


  Confirmation bias, also called confirmatory bias or myside bias, is
  the tendency to search for, interpret, favor, and recall information
  in a way that confirms one's beliefs or hypotheses, while giving
  disproportionately less consideration to alternative possibilities.


A feature of this bias is belief perseverance:


  ... when beliefs persist after the evidence for them is shown to be false ...


Confirmation bias is an umbrella term for a variety of strategies and effects that may be applicable in different situations, including self-justification, self-verification, attitude polarization, escalation of commitment, cherry picking, etc, etc.  See the duplicate questions I listed in the comments above for more varieties of these.  You may find that some sub-category of confirmation bias is more apt to your question.

Note: Cognitive dissonance refers to the cause of a number of possible inconsistency reduction strategies, of which belief perseverance is one.

Note: Denial refers to an ego-defence mechanism - ie, it applies only if the person feels personally threatened by the inconsistency.