Research on motivated reasoningsuggests that people tend to believe what they want to believe. Muslims in particular have reason not to want to believe that mass murder on 9/11 was carried out by co-religionists in the name of their faith. This may lead some to embrace a defensive narrative where they are victims of a larger conspiracy by the U.S. or Israel to launch a self-serving war on Islam
People believe what they want to believe
Interesting links DJS. I think this comment says it all, people believe what they want to believe.
You could provide a mountain of proof from climate scientists that global climate change is real, caused by man and a problem, but people will believe Rush Limbaugh, because Rush makes them feel smart that they haven't been taken by the crazy scientists and they would rather not have to give up their 15mpg Ford F-350 That they don't even use to haul anything.
It explains why a narcissistic airbag like Trump leads in the polls right now. He tells people like this what they want to hear. He was hopelessly lost in the debate as he had no knowledge of foreign policy, but it doesn't matter to his fans.
The same thing with the moon landings, 9/11 conspiracy theories, etc. People believe what they want to believe.