Why people cling to religion
I have concluded that all those people who do not accept the demonstrations of science and still consider “intelligent design” valid are either emotionally unwilling to consider the science dispassionately, or intellectually incapable of understanding the processes described. As far as I can see, the causal basis of creationism is the sheer inability of a lot of people to understand the descriptions of the processes by which the universe as science knows it arose from the big bang, and by which on this planet living organisms arose from the chemistry of the environment on the earth. Faced with the books of Sawkins and all the others, many of the religious people simply lack either the intellectual training in scientific discourse necessary to understand those discussions and descriptions, or the pure intelligence power needed to develop in their own minds the mental models being described, and so if they were to accept the scientific explanations it would mean trusting the people presenting those descriptions, which is what they do in the rest of their lives where somebody explains something to them and they are unable to actually follow the explanations.
Such people are used to either trusting the people who are explaining something to them, or else rejecting what they are being told, simply based on who the people are, and not on the coherence of the explanation because they are not bright enough to follow the explanation.
I said just now “a lot of people” and I must now state
my suggested explantion for the others.
For there are some (only a very few, I hope) very highly intelligent people
(including members of Mensa,
who in order to join have IQs in the top 2 per cent of the population)
who are either Creationists to some degree or at least go along with the Intelligent Design argument
and resist the rational empirical argument about the origins of the univese and life on earth.
As far as I can tell, the explanation for the position these people take
is that they reject rational argument for emotional reasons.
Emotional attachment to religious beliefs is often very strong,
sometimes dating back to childhood and a strict church-going upbringing,
but sometimes after a religionless but unhappy childhood
dating to a sudden religious conversion in adulthood
at a time of emotional or other difficulty or stress.
The effect of emotional attachment even in very highly intelligent peopleis that
the mind is brought to bear to devise apparently logical justifications for their position.
I myself have observed among Mensa members such ploys as
asserting that “science” only means “knowledge”
and that knowledge includes not only what can be proved by experiment but what can be read in books.
However, all this does is to put discussion on the subject back about 300 years
to the era before the scientific method had started to be established,
when scholars still revered figures like Aristotle so greatly that
anybody who questioned anything in one of his books was almost in danger of being burnt at the stake for heresy.
On the emotional hold that religion has on (apparently) the majority of the human species, one can point to the trauma suffered by young children when they first discover that there is no Father Christmas (it is your parents!). When it is not an ogre, such as under the Inquisition or the Taliban, religion is mostly a comfort to its believers. The idea that someone "up there" is looking after you, someone is always there watching you and to be prayed to in times of crisis, is such a comfort that most human beings cannot face the fact that it is all delusion, and I see no more reason to disrupt their contentment than I do do go around the place telling small children the truth about Santa Claus. See Can we disillusion them?.