20 On the contrary: “If your enemy is hungry, feed him; if he is thirsty, give him something to drink. In doing this, you will heap burning coals on his head.”

21 NIV:Do not be overcome by evil, but overcome evil with good. (Rom. 12:20-21)

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Do you feed your enemy when he/she is hungry? Or are you always afraid of him/her killing you or hurting you? Do you always feed your enemy when he/she is hungry or you are always praying for his/her downfall (death).

If Jesus is your master (model), if you are a child of God you have to feed your enemy when he is hungry because that's was what Jesus do, he never despise his enemies instead he blessed them and also pray for them, if you say you are following Jesus then why doing what Jesus didn't do such as praying for your enemy downfall (death), despising them and hating them etc. Jesus didn't do any of this instead he loves his enemies.

Why overcoming evil with evil when Jesus told you to overcome evil with good, if you are a Christian (child of God) do you overcome evil with good? Or do you seek for revenge,
Jesus says that

“It is mine to avenge; I will repay,” says the Lord.

Even the Bible makes us to understand that vengeance belongs to God not you or me but God. If so then why are you struggling for revenge when you know too well that vengeance is not yours.

Do not take revenge, my dear friends, but leave room for God’s wrath, for it is written: “It is mine to avenge; I will repay,” says the Lord. (Rom. 12:9)

All you have to do to your enemies is to feed when they are hungry, when they are thirsty give them something to drink, this is what you can do to your enemies apart from this you can't do anything because vengeance is God and you as a Christian can't overcome evil with evil but evil with good.