While people could be rational most of the time, they often don’t choose to be. This is especially true when it comes to religious faith. Sure, few religious people utilize their faith in dealing with common problems: when they have a flat tire, they don’t get out of their car and kneel down and pray for a miracle fix; when they have physical maladies, with notable exceptions (such as Christian Scientists), they usually consult physicians and don’t leave a cure solely up to their god. All in all, most people these days generally confine their reliance on faith to their minds and don’t let it rule their plans of action.
Why then is faith still so popular, even in advanced societies? It’s not because faith is actually useful or effective. In large measure, it is because faith is promoted by its champions by associating it with desirable things such as art, marriage, love, and even science (as in the case of the Templeton Foundation and its cadre of religion-friendly scientists). The concept of free will, too, is left to the domain of faith, because atheists tend to be materialists, a stance that for many precludes contracausal free will or causal agency in the natural world.
It is, I submit, because of this fraudulent association of faith with desirable things in our lives that it stays around. Never mind how little it actually delivers. Never mind all the time and propaganda it gets from certain circles. Association with aspects of our lives that most of us deem important, however misguided, makes faith persist.
It was Immanuel Kant who defended a basic skepticism about the human mind so as to make room for religion. He figured, maybe rightly, that if one can discredit human thinking as a road to understanding the world, many of us will allow faith to make the big difference for us. And sure enough, if we come to the conclusion that the only way to have morality and free choice is to reject naturalism, we will usually choose the former and abandon the latter. Not that we would actually give up on naturalism; we would just refuse to endorse it as the big picture. We would buy into some kind of rough-and-ready hybrid instead, some dualism of nature and spirit.
Faith is a dead end for most purposes, but because the alternative—relying on the study of nature—gets so closely linked with denying morality and free choice and all that we think these make possible for us, people cling to faith despite its ultimate poverty. For no one can reasonably give up morality; even those who advocate doing so fall right back into making use of it when they insist that sensible people should not believe in it and should see it as bogus, and they often wax rather righteous about it all. Nor is free will easily rejected. After all, the choice to reject it is itself supposed to confirm its existence! Then, if you add that most of the sublime aspects of human existence would have to be abandoned if a naturalist approach were to triumph, it becomes clear why, despite its ultimate and evident uselessness, faith has staying power.
Among many of the so-called “new atheists,” all this comes across very clearly. Just see how many of them defend the idea that human beings are free to make choices that aren’t imposed on them by various factors over which they have no control! How many of them believe that morality is real in the sense that it involves choosing between right and wrong conduct! (Or, by extension, that there are rational standards for deciding how to act.)
Perhaps there is a way to reconcile ordinary life with such barren viewpoints, but it is very doubtful that the idea will sell well. If people accept that without faith there is no love, no beauty, no right versus wrong, and so on, they will very probably opt for faith even if doing so is irrational. Doing this may have nothing in support of it except for one thing: the alternative, a life without faith that so many take to mean a crassly materialistic life, is unacceptable to most.
Indeed, it appears that the main obstacle to the spread of a naturalist—or secular humanist—approach to human life is that too many of those who defend these life stances have mistakenly denied too much that makes human life interesting and unique.