“The attempt to prove God’s existence is either useless or unsuccessful. It is useless if the searcher believes that God is a rewarder of those who seek Him. And it is unsuccessful if it is an attempt to force a person who does not have this pistis by means of argumentation to an acknowledgment in a logical sense.”
Dict. Dogm., De Deo I, p. 77.
Translated by Louis Berkof in Systematic Theology. Available as pdf here.