There is no doubt that the debate over how we generate and justify our beliefs is immensely important . . . . In recent years, considerable attention has been paid to the way in which people sustain their belief systems. The evidence is disturbing, especially for those who continue to believe in the Enlightenment vision of complete objectivity of judgment in all things. Yet there is growing evidence that belief systems - whether theistic or atheistic - are neither generated nor sustained in this way.
Cognitive psychological research has demonstrated repeatedly that people "tend to seek out, recall, and interpret evidence in a manner that sustains beliefs." The interpretation of data is often deeply shaped by the beliefs of the researcher. These implicit beliefs are often so deeply held that they affect the way in which people process information and arrive at judgements. Both religious and anti-religious belief systems are often resistant to anything that threatens to undermine, challenge qualify, or disconfirm them. Deeply held assumptions often render these implicit theories "almost impervious to data."
Some Christian and Islamic writers seem unwilling to examine their deeply held beliefs, presumably because they are afraid that this kind of thing is bad news for faith. Well, maybe it is - for intellectually deficient and half-baked ideas. But it doesn't need to be like this. There are intellectually robust forms of faith - the kind of thing we find in writers such as Augustine of Hippo, Thomas Aquinas, and C. S. Lewis. They weren't afraid to think about their faith, and ask hard questions about its evidential basis, its internal consistency, or the adequacy of its theories.*
*Alister McGrath, Dawkins’ God: Genes, Memes, and the Meaning of Life. Malden, MA: Blackwell Publishing, 2007, p. 82, 83; with quotes from Richard E. Nisbett and Lee D. Ross, Human Inference: Strategies and Shortcomings of Social Judgment. Englewood Cliffs, NJ: Prentice Hall, 1980, p. 192, 169.