Pretty simple. Many are wolves in sheeps clothing. They come to church to prey upon, not pray with those befuddled believers. Fo example Trump was deeply influenced by Dr. Norman Vincent Peale (The Power of Positive Thinking) while a Presybreterian who was even discreditied by the Church for being assholish. Now Trump proclaims his theocracy routienely and evangleicals love him - but it seems the focus is political, not religious. The leaders are misleading the believers for their own enrichment.

I haven't got a clue

The Atlantic had a good article on this and perceptual bias. It went on about how facts alone won't change beliefs. A person with a firm conviction, when confronted with facts will question your sources or go on to attack some part or person unrelated.

I believe it is cognitive dissonance:
"The state of having inconsistent thoughts, beliefs, or attitudes, especially as relating to behavioral decisions and attitude change."

--Oxford Dictionary.