Do not be overcome and conquered by evil, but overcome evil with good.
Romans 12:21 AMP
The context of this scripture is society. Dealing with human persecutors. That is to say human beings that unjustly do harm to believers. This is the evil that is being spoken of. It is inevitable in society that there will be people that do you harm. They may gossip, slander, steal from, accuse, manipulate, abandon, betray, bewitch, etc.
Scripture says that these things can overcome and conquer you. It is a possibility. Remember that this verse was not written to sinners. It was written to believers. It is a possibility that the evil perpetrated against a believer may overcome and/or conquer them. But only if they let it.
How is a believer who has all authority overcome and conquered by evil? A believer is overcome and conquered by evil when they retaliate against their persecutors. When someone does you wrong and you repay them for their wrong, you may feel good when you do it but by so doing, you have been overcome and conquered by evil. You have given in to temptation and allowed yourself to be used by the evil one.
Scripture instructs us that in order to overcome evil we must do good. This shows us that good is more powerful than evil. Good conquers evil the same way darkness flees light. So, as an example, when someone slanders your name, the Biblical standard is not to cuss them out but rather to be kind to them. This is how you overcome evil with good.
When you retaliate, you become a vessel of evil. However, when you forgive and act in kindness, you overcome evil. Practically, this is achieved in two ways:
- Personally you overcome the temptation to be used by the devil. Furthermore, forgiveness frees you from soul tormentors such as bitterness and anger.
- With regards to your enemy, you “heap coals of fire on their head.” The expression “heap coals of fire on their head” refers to an ancient practice in which a penitent person carried a bowl of burning embers on his head to show his shame and guilt. So, by analogy being kind to an enemy gives them opportunity to repent which would not be available if one repays evil for evil. So being kind to an “enemy” deals with the real enemy.
Unesu Godza 
Love the work, keep pushing
Amen