Relativism: The view that truth is relative (no absolute truth) and may vary from individual to individual, from group to group, or from time to time, having no objective standard.
Fideism: A doctrine of Abbe Bautain which attempted to justify the teachings of Christianity by the theory that all knowledge rested upon premises accepted by faith. The premises of religion are to be found in the tradition of the Synagogue and Church. This tradition needs no rational criticism because it is self-critical. The doctrine was condemned in 1840 by Pope Gregory XVI. -- G.B.
Pope Benedict: Believers need to use common sense and intelligence, while free-thinkers need God in order to see things in their proper light, with proper modesty. Man has a mind but his mind is to be used subject to divine arbitration: under God. God is the ultimate Judge, though we, on earth, have many judgments that we need to make, in His name; but always in his name.
E.g. The question of clothing etiquette leaves much leeway, while "thou shalt not commit adultery" (and Christ's "thou shalt not covet") does not!