One of the basic mechanisms of a cult is absolute belief in a particular set of beliefs, whether it be religious or otherwise. Whatever evidence offered that conflicts with core beliefs not only can be washed away, but must be so treated, using any means necessary. The belief at times approaches the clinical definition of a delusion- a fixed false belief that cannot be changed by evidence or argument open to most people in society. We do not need shape changing lizards- this behaviour is apparent in politics, football fans, pressure groups and many other social structures. including internet fora!
Look for a Fixed Belief, Strong Leaders, Group Compliance and devaluation of non-group members.
There are two cults operating here and an uneasy middle ground, though the middle ground is often pulled into the battles because they are seen as opponents by one or both sides.
The tenet of the Anti-McCanns is that despite several extensive examinations that show clearly that they are at fault, they have not been made to suffer for their misdeeds. The corollary is that cult members and the public should be free to libel, harass and abuse them, even though this is outside the law. They often claim collusion by powerful forces and a conspiracy to avoid the McCanns being brought to Justice.
The tenet of the Pro-McCanns is that there is nothing possibly morally dubious about their actions- that not only are they not technically or legally culpable for Madeleine's disappearance, they are also morally free from culpability, and those that say they are culpable are wrong in everything they do.