The research literature reveals religion as a major barrier to the acceptance of the evolutionary theory. What is it exactly about religiousness that causes people to reject scientific evidence?
Prominent Proposals
While multiple proposals that try to explain why evolution deniers deny evolution, I have select two popular ones.
The first proposal suggests that self-imposed ignorance is to blame for why evolution deniers deny evolution. According to supporters of this proposal, evolution, deniers reject evolution out of simple ignorance of the facts, evidence, and mechanisms. That said, there is no evidence that simple education on the facts, evidence, and mechanisms of evolution help understand evolution is real.
The second proposal, on the other hand, claims evolution deniers reject evolution because they lack scientific reasoning ability. That said, there are a sizeable number of academically gifted people who are skeptical about evolutionary theory.

Solar System Controversy
The evolutionary theory is not the first theory that was rejected by people although evidence supported the theory. For example, the infamous solar system controversy.
As you know, the earth is the center of the universe was the common wisdom in Europe before the spread of Christianity. Although Christian scriptures were silent on orbits of heavenly objects, the Catholic Church adopted the Earth-centric universe as one of its teachings.
During the dark ages, the Catholic church found an earth-centric universe appealing, especially because in their view by placing the earth in the center of the universe, God was validating how special and powerful the earth was. Therefore, the idea of a moving earth was widely seen as foolish. Besides, if the earth were to be orbiting the sun people would feel the movement.
As expected, it did not sit well with the Catholic church when Galileo Galilei discovered the solar system. The church felt it was too much invested in an earth-centric view of the universe. The church leaders believed that accepting a model where the earth was just another planet orbiting the sun was an existential threat to the church.

Handwashing Controversy
In the twenty-first century, it is incomprehensible to us, but believe it or not, washing hands was once controversial advice given to doctors.
In 1846, to evaluate his conclusions on the importance of hygiene, the Hungarian doctor Ignaz Semmelweis mandated doctors at Vienna General Hospital to wash their hands before and after treating patients. Unsurprisingly, the death rate of patients at the hospital fell dramatically, and Semmelweis concluded that the hand hygiene of doctors prevented infections.
It sounds like a bad joke, but believe it or not, in the mid-nineteenth century, the popular view among physicians was it was water that caused complications in patients. For Hungarian physicians, as well as physicians worldwide, accepting Semmelweis’ proposition meant admitting the fact that physicians had been causing the death of patients in multitudes. Despite contrary evidence, physicians wanted, and insisted to believe it was water that caused complications in patients, and stopped the practice of washing their hands.

One's Own Reality
Nearly two decades ago a close friend of mine had a nervous breakdown while he was going through a stressful period. For the sake of ease, I will call him Bill.
Bill believed his wife was cheating on him with his brother, most people in his life were a part of a huge conspiracy against him, his phones were tapped, his house was bugged.
My friend held onto his fictitious reality because he genuinely believed his reality with absolute certainty, so much so that, there were times he made others doubt themselves for a moment or two.
People close to Bill thought the best strategy to deal with the crisis was to make him face reality by providing “evidence” of why he was wrong. Every time he would listen to us carefully and make up a reason why his reality was still true, and ours wrong.
Eventually, what happened was that he “discovered” we were all a part of the said conspiracy too, and that was why we were trying to convince him he was wrong.
Why people around Bill failed to help him was simple. We did not fail due to a lack of “evidence” on our side. Changing his mind has never been on the table for Bill from the get-go. His fictional reality was so much integrated into his personality that when we produced evidence that contradicts his assumptions, thoughts, and beliefs, we were inadvertently attacking Bill personally.

Conclusion
It is my opinion that for most evolution deniers, rejecting evolution is part of their culture, which they are as is proud of. Some deniers continue to deny evolution as long their religious leaders do, some other deniers are trapped because they feel they are too much invested in the rejection of evolution. And ultimately, some evolution deniers complain about evolutionary theory’s “lack of evidence” as if accepting evolutionary theory is on the table but it is the lack of evidence that keeps them deny evolution.
In the distant future, however, I trust rejecting evolution will not be any different than rejecting the solar system or the germ theory of disease. Scientific facts always win, one way or another.
[…] Who Are Those Who Deny Evolution? […]
[…] Who Are Those Who Deny Evolution? […]
[…] Why Do Some Disbelieve in Evolution? […]