Romans 12:20

But if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire upon his head.

This is an amazing scripture. The writer once heard of a woman involved in bitter quarrels with her husband. Seeking counsel, she was asked, "Have you tried heaping coals of fire on his head?" She replied, "No, but I tried a skillet of hot grease!" She, like many others, failed to realize that Paul here used a figure of speech, a style of rhetoric often found in the sacred scriptures. As Batey noted:

The original meaning of this figure of speech has been lost, but Paul suggests that the enemy will burn with shame for his abuse of one who loves him.[19]

Paul, throughout this chapter, has consistently elaborated the strategy of overcoming evil with good, the same being the ancient strategy of the Lord, announced centuries earlier in the book of Proverbs, thus:

If thine enemy be hungry, give him bread to eat; and if he be thirsty, give him water to drink: for thou shalt heap coals of fire upon his head, and the Lord shall reward thee (Proverbs 25:21,22).

Rather than delving into the strange and even bizarre interpretations people have suggested for this passage, it seems that it would be better to accept the explanation offered by Batey, to the effect that the actual meaning of the figure is lost. Whatever might have been the meaning, the motive of providing food and drink for an enemy cannot be that of increasing his punishment, nor of aggravating his guilt, the true purpose, or motive, being the effective discipline of the Christian's own spirit and likewise the subduing of enmity within the adversary. This alone would fit the strategy announced in the next verse.