The pastor of the New Life Church, a charismatic fundamentalist sect, argues that they (we) cannot. Pastor Ted Haggard has his congregation engaged in spiritual warfare with Satan over the souls of Colorado Springs. Quite literally.
Needless to say, both the journalist and I the listener were, in fact, utterly baffled by this behavior. Well, I wasn't so much baffled as both revulsed and rather sad for these folks.
But back to the question -- is faith something comprehensible only by the faithful? Or, did I just change the question?