Why does the Lord ask you to love your enemies and to return good for evil?
That YOU might have the benefit of it. It does not injure him (your enemy) so much when you hate a person, especially if he is far removed and does not come in contact with you, but the hate and the bitterness will canker your unforgiving heart...
We pray for our enemies. This will soften our hearts, and perhaps theirs, and we may better seek good in them. And this prayer should not be confined to national enemies but should extend to neighbors, members of the family, and all with whom we have differences.
The Teachings of Spencer W. Kimball
I have a testimony of this!