What is faith? The word is frequently used in a secular sense, for example, to have faith in the British legal system, or faith that your football team will do well this season. To some extent, therefore, faith is regarded as lacking certainty and is distinct from what we usually refer to as knowledge. You cannot know for sure that your team will not be relegated. The term, in this respect, is synonymous with ‘trust’ or ‘confidence’ and indicates a lack of sufficient evidence, or any evidence at all, for that matter. However, to say someone has faith in God seems to be making much more of a claim to knowledge than in the secular sense.

To an extent, all the arguments put forward so far are an attempt to show that belief in the existence of God is in some way rational. However, certain philosophers, such as Kierkegaard, have argued that rationality has little to do with it: what matters most of all is faith, which is, quite simply, an irrational commitment. Other philosophers, notably Kant, have emphasized that it is through the power of reason that the existence of God can be postulated. What we shall examine in this chapter is the relation between reason and faith and the role of reason in determining the existence of God.