6 One cannot better explain the difference between these two fears, the one which charity casts out, the other chaste, which endures for ever, than by putting the case of two married women, one of whom, you may suppose, is willing to commit adultery, delights in wickedness, only fears lest she be condemned by her husband. She fears her husband: but because she yet loves wickedness, that is the reason why she fears her husband. To this woman, the presence of her husband is not grateful but burdensome; and if it chance she live wickedly, she fears her husband, lest he should come.
Such are they that fear the coming of the day of judgment. Put the case that the other loves her husband, that she feels that she owes him chaste embraces, that she stains herself with no uncleanness of adultery; she wishes for the presence of her husband. And how are these two fears distinguished? The one woman fears, the other also fears. Question them: they seem to make one answer: question the one, Do you fear your husband? She answers, I do. Question the other, whether she fears her husband; she answers, I do fear him.
The voice is one, the mind diverse. Now then let them be questioned, Why? The one says, I fear my husband, lest he should come: the other says, I fear my husband, lest he depart from me. The one says, I fear to be condemned: the other, I fear to be forsaken. Let the like have place in the mind of Christians, and you find a fear which love casts out, and another fear, chaste, enduring for ever.
Source: Homilies on the First Epistle of John (New Advent)