(Romans 12:20) Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head.
A Protestant pastor of mine once taught that in Bible days people would carry coals on their heads in some sort of fireproof container. By heaping these coals of fire on an enemy's head you are giving them a gift, a blessing, so they can start their own fire. I wonder why the enemy would calmly stand there while you transferred coals from your head to his (wouldn't you both take the containers off your heads first before transferring the hot coals?)
Needless to say, this sounded fishy to me so I did my own Bible study of the topic.
Many who interpret this verse interpret the phrase "heap coals of fire on the head" as figurative and give it all sorts of meanings such as:
I don't care for the figurative interpretation of the Bible preferring instead to interpret it in a strictly literal manner. Once you start using figurative interpretation the Bible becomes gibberish. In the very early days of the church many of the Early Church Fathers started using a figurative method of interpretation. The results of this are (then and now) that you can support any wacky idea you want to by making words and phrases figuratively mean whatever you want them to.
In battle if you were inside a city under seige, you might pour down ashes on the heads of those below trying to breach the walls. In Romans 12:20 you don't defend yourself this way; instead, you feed them and give them drink.
Romans 12:20 is in the context of Paul teaching about revenge. He gives the example of how to relate to your enemy as an illustration of his teaching that we should not vent our anger on others nor seek revenge. Instead, we should bless them and let God judge them. God will heap the coals of fire of his judgment on them as required; it is not our place to do this.
(Romans 12:19) Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord.
The following are other Bible passages using the phrase "coals of fire".
(Leviticus 16:12,13) And he shall take a censer full of burning coals of fire from off the altar before the LORD, and his hands full of sweet incense beaten small, and bring it within the veil. And he shall put the incense upon the fire before the LORD, that the cloud of the incense may cover the mercy seat that is upon the testimony, that he die not.
In this passage the coals of fire are part of the sacrificial rite in which incense is lit and the fragrance of the smoke pleases God. When we in faith offer various sacrifices to God for our sin, God forgives us.
(2 Samuel 22:13) Through the brightness before him were coals of fire kindled.
(Psa 18:13) The LORD also thundered in the heavens, and the Highest gave his voice; hail stones and coals of fire.
In these verses, the phrase "coals of fire" refers to the flashes of lightning in a storm. The context seems to be God's greatness, his mercy, and his judgment of sin. When God judges sin there are bright flashes of "coals of fire." God does not judge passively, but actively for all the world to see.
I interpret passages such as these literally. Since God is the focus of attention we should expect the action to be occurring in the highest heaven were he lives. He literally uses hail, burning coals, and the like in executing judgment. When this filters down to the physical realm we experience such things as thunder, lightning, invasions by armies, plague, etc.
(Proverbs 25:21,22) 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.
The same as Romans 12:20. Paul is quoting this passage. He has memorized many, many Old Testament passages or he is somehow able to look them up in his Old Testament scrolls. This would be hard to do without a computer or without indexes to verses.
(Song of Songs 8:6) Set me as a seal upon thine heart, as a seal upon thine arm: for love is strong as death; jealousy is cruel as the grave: the coals thereof are coals of fire, which hath a most vehement flame.
In this verse, the phrase "coals of fire" refers to coals which are burning. True love with a lifelong commitment is intensely energetic and passionate just as burning coals are when compared to coals which are not burning.
In this passage the word "coal" and the phrase "coals of fire" are figurative because the writer says they are. He says that the coals of love are burning coals — two back-to-back metaphors.
(Ezekiel 1:13) As for the likeness of the living creatures, their appearance was like burning coals of fire, and like the appearance of lamps: it went up and down among the living creatures; and the fire was bright, and out of the fire went forth lightning.
These angels are bright. It is common in the Bible for angels and humans who are "on fire" and energized by God to glow brightly.
In this passage the phrase "coals of fire" is figurative because the writer says so. It is a simile as evidenced by the use of the word "like" — "like burning coals of fire."
(Ezekiel 10:2) And he spake unto the man clothed with linen, and said, Go in between the wheels, even under the cherub, and fill thine hand with coals of fire from between the cherubims, and scatter them over the city. And he went in in my sight.
The angel scatters these coals of fire over Jerusalem. In the context we clearly see that this passage is discussing the topic of God's judgment on his wayward people. Therefore, the phrase "coals of fire" refers to judgment.
I believe this is literal, not figurative. In the spiritual, heavenly realm where this vision is actually occurring, literal coals of fire are literally poured-out on the city. Back in the physical realm, the inhabitants of Jerusalem experience this in the form of various invasions by enemies.
Thus, by heaping coals of fire on someone you are in your soul and in your mind casting judgment on them in the hopes that they will experience calamity in the physical realm as a consequence for their sins against you. In Romans 12:20 we are told to not do this, to let God be the judge, to let God heap the coals of fire on your enemies.