A more widely used meaning for the term is that fideism essentially teaches that reason is more or less irrelevant to faith. Specifically, fideism teaches that arguments for the existence of God are fallacious and irrelevant, and have nothing to do with the truth of Christian theology. Its argument in essence goes:
A more sophisticated form of fideism is assumed by Pascal's wager. Blaise Pascal invites the sceptic to see faith in God as a cost-free choice that carries a potential reward. He does not attempt to argue that God indeed exists, only that it might be valuable to assume that it is true.
Some theologies, however, strongly reject fideism. The Catechism of the Catholic Church, representing Roman Catholicism's great regard for Thomism, the teachings of St Thomas Aquinas, affirms that it is a doctrine of Roman Catholicism that God's existence can indeed be demonstrated by reason. Likewise, a tradition of argument found among some Protestant fundamentalists seeks to argue that respect for Jesus as a teacher and a wise man is logically contradictory; either He was insane or a charlatan, or he was in fact the Messiah and Son of God. Cf., Christological argument
While the centrality of issues of faith and its role in salvation make fideism of this sort an important issue for Christianity, it can exist in other revealed religions as well. In Islam, the theologian Ghazali strikes a position similar to Tertullian's fideism in his Talafut al-falasafa, the "Incoherence of the Philosophers." Where the claims of reason come into conflict with revelation, reason must yield to revelation. This position drew a rejoinder from Averroes, whose position was more influential in Thomist and other mediŠval Christian thinking than it was in the Islamic world itself. Ghazali's position of the absolute authority and finality of divine revelation became the standard of orthodox Muslim exegesis.