A condition whereby a person fully capable of intellectual discourse suspends his/her rational faculties.
Jack: You cannot see the wind so therefore you cannot prove it exists—but it's there! The same thing applies to god, he is everywhere even though we can't see him.
Jill: On the contrary, we can feel the wind and see it carrying particles. We can't 'see' it in the traditional sense but—
Pete: Jill, ju-just, just, don't worry about it. Jack's suffering from bible brain.