Faith, demonstration, and friendship

In his On the Advantage of Believing, Augustine reflects on the necessity of belief but also on the danger of being overly credulous. He comments, in part,

But now consider, you will say, whether in religion we ought to believe. For even if we concede that it is one thing to believe, another to be credulous, it does not follow that there is no fault in believing in religious matters. What if it be a fault to believe and to be credulous, as it is to be drunk and to be a drunkard? One who holds this view as certain, it seems to me, could have no friend. For, if it is base to believe anything, either he acts basely who believes a friend, or, in not believing a friend at all, I do not see how he can call either him or himself a friend…. For there is also no friendship at all unless something is believed which cannot be demonstrated by positive reasoning. (Util. cred. 10.23–24)

To be sure, reasons are important, but reasons have force within the context of some kind of faith toward the source from which the reasons derive.