The idea that religious belief is some sort of illness or irrational stance, is not uncommon in Western Europe. The philosopher of religion, Alvin Plantinga, in his book Warranted Christian Belief advances a detailed account of the rationality of religious, and especially Christian, theistic belief. In the book he explains:

a belief has warrant if and only if it is produced by cognitive faculties functionally properly in a congenial epistemic environment according to a design plan successfully aimed at the production of true belief.

He explores the question, is Christian belief intellectually acceptable? He is not addressing the question of whether it is true or false, but whether it is reasonable, or rational to hold.

First, he asks whether in principle it is possible to have knowledge of God. If knowledge of God is not possible then beliefs in God would be unreasonable. If God is part of the noumenal realm, rather than the phenomenal realm, and if we can only access the phenomenal realm, then how can it be possible to perceive God? If God is not a finite reality then nothing in our experience can be identified as God. If nothing in our experience can be identified as God then God refers to nothing.

However Christians give accounts of perceiving God, in ways such as those recorded in the Bible – through the burning bush to Moses. In addition, if God is infinitely powerful, omnipotent, then why would he not be able to manifest himself in our experience? It seems unreasonable to place on such a God the inability to make himself felt in some way.

Of course there are those who argue that God is in fact an imaginative human construct, and that our use of the word ‘God’ is in fact associated with a human idea or symbol but that such an idea could not create the world or be omniscient. However, this rejects that which Christians claim, and so effectively redefines God in to something Christians do not hold to believe (in the most part). This is a rehashing of secularity. In other words this is not an argument against a Christian theistic belief but an argument for an alternative belief about religion.
Plantinga then turns to the question and examines the idea of justification.

Critics claim that Christian belief is not rationally justified or justifiable: what, precisely, is the infirmity or defect they are ascribing to the Christian believer? What, exactly, is the question?

What are Christians accused of lacking? He suggests this criticism arises out of an idea called foundationalism. He explores the idea that theism is rationally acceptable only if there are good arguments for it. He suggests that this treats religion like a scientific hypothesis, but questions whether that is reasonable. He suggests that this lays down a standard that the very argument itself cannot meet. Foundationalism itself fails to meet its own standard used here to reject religion. In fact it leads to the rejection of most of our beliefs, not just theistic ones.

How much meets the classical conditions for being properly basic? Not much, if any. I believe that I had cornflakes for breakfast, that my wife was amused at some little stupidity of mine, that there really are such ‘external objects’ as trees and squirrels, and that the world was not created ten minutes ago with all its dusty books, apparent memories, crumbling mountains, and deeply carved canyons. These things, according to classical foundationalism, are not properly basic; they must be believed on the evidential basis of propositions that are self-evident or evident to the senses.

There are many beliefs which we rely on that in fact cannot be provided with good arguments that make them scientifically proven. The existence of external objects are difficult to separate from our perception. Memories are hardly scientifically proven and yet we believe them and rely on them. In short, the standard that people make when critics suggest Christian theism unreasonable, is so high than many everyday beliefs would also fail the test.

Finally, Plantinga explores the idea of warrant. He considers those who argue that religious belief is wish fulfillment (Freud), or some sort of dysfunction (Marx). He notes that both begin their arguments from a position that claim theism is false. This is not argued, merely stated or asserted as a given. He continues to explore classic arguments against Christian belief (which he calls defeaters) and makes counter-cases. He believes none of these make serous challenges to the warrant Christian belief can enjoy, if it is true. The crucial difference here is not that he is arguing Christian beliefs are true, but that they are warranted if true.

For more read a detailed review of the book: www.proginosko.com/docs/wcbreview.html.