"In a fallen world, the only currency of love is suffering. Indeed, the only way to gauge the extent to which someone loves us is by what that person is willing to suffer for us. Without the cost incurred by suffering, love among fallen creatures becomes cheap and self-indulgent. Suffering removes the suspicion that the good we do for one another is for ulterior motives, with strings attached, a quid pro quo."
--William A. Dembski [pdf]