Jesus taught people to love their enemies. It was new and people never heard before.

It was contrary to the history of Jewish people. God used to order Jewish people to fight against enemies and destroy them.

Matthew 5:44 International Standard Version (ISV)
But I say to you, love your enemies, and pray for those who persecute you, 

The enemy, however, is a human being and the human being is a changing entity, as the words "the enemy of yesterday is the friend of today" shows.
Even if one seems to be a good person, he may be a criminal tomorrow. Thus there's a possibility that today's friend may be an enemy tomorrow.

In the past, 'good and bad' were made by God. But is it the right thing for us to judge a man to be bad and be an enemy?

The human mind, emotions, sense of values, and situations create enemies. Human thoughts and feelings make a bad person and an enemy.

There is originally neither a good nor a bad person.
A person is not an enemy. Our mind makes the enemy. The human mind tries to find reasons to create enemies to satisfy their emotions.

People violate laws and become criminals. But they are not bad people, but criminals.

Even though they are criminals, it doesn’t mean they are bad people.

People are just people. People are not enemies.

Therefore there’s no reason to love enemies. "Don’t make enemies!" is the right expression, for you create enemies by your thoughts and emotions.

Never make enemies!

　　

Flowers themselves are not conscious that they are beautiful. Flowers only bloom by inherited genes. People look at it and think that it is beautiful. Is it only human beings who think that they are beautiful from their point of view?