To answer your good question, let’s look at Romans 12:19-21 which says, “Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord. 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. Be not overcome of evil, but overcome evil with good.” 

This portion shows us clearly that we are not to seek vengeance on those who have used or abused us.  Vengeance belongs to the Lord for only He can judge righteously.  The Lord Jesus addressed this issue in Matthew 5:44, “But I say unto you, LOVE your enemies, BLESS them that curse you, DO GOOD to them that hate you, and PRAY for them which despitefully use you, and persecute you.”  Here we learn that for every evil act done against us, we should respond with a positive God-like reaction.  This benefits the one who is persecuting us and it glorifies our Lord. 

We are taught here in Romans 12:19 that we are supposed to “give place unto wrath.”  That means we should leave the work of retribution to the Lord.  The Lord guarantees righteous justice by telling us, “I WILL REPAY.”  If it is a grievous wrong that is done to us, something that may even be criminal, the Lord may choose to use the legal system to exact His revenge.  We read of the judicial system in Romans 13:4, “For he is the minister of God to thee for good. But if thou do that which is evil, be afraid; for he beareth not the sword in vain: for he is the minister of God, a revenger to execute wrath upon him that doeth evil.” 

But, for those who choose to persecute us for our testimony for the Lord, or those who hate the Lord and therefore hate us (read John 15:18), our response should be as we just read…do good to them who hate us!  So, if our enemy should be hungry, we should feed him.  If he is thirsty, we should give him something to drink.  These are nice, loving, and useful acts to help those who hurt us.  We have this example from the Lord Jesus in 1 Peter 2:21-23, “For even hereunto were ye called: because Christ also suffered for us, leaving us an example, that ye should follow his steps: Who did no sin, neither was guile found in his mouth: Who, when he was reviled, reviled not again; when he suffered, he threatened not; but committed himself to him that judgeth righteously.”  In the face of hatred and persecution, the Lord simply left these things to His Father for His righteous judgment.  The Apostle Paul gave a similar expression as he committed his cares to the Father’s hands.  He said in 2 Timothy 1:12, “For the which cause I also suffer these things: nevertheless I am not ashamed: for I know whom I have believed, and am persuaded that he is able to keep that which I have committed unto him against that day.”

Now, how are we to understand the phrase, “for in so doing thou shalt heap coals of fire on his head?”  I think we can recognize that this is not an act of cruelty or vengeance against our enemies for we were just taught not to seek vengeance.  Rather, the thought is that if we become a benefactor to the one who has treated us so harshly, our good works would convict this man’s conscience and bring him to repentance.  The desire is that we are able to cause him to be ashamed because of the love shown to him in the face of hatred. 

When we show love to those who mistreat us, the Lord is pleased, and He will honor us for these acts which manifest His love in us as believers.  Proverbs 25:21-22 assures us, “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.”

Lastly, may we heed the instruction and warning of Romans 12:21, “ Be not overcome of evil, but overcome evil with good.”  (CC)  (583.6)