Everyone admits, at least in theory, even those who do not have high ideals, that loving even enemies is a moral teaching, that it is right. 
The second Isaiah preached: “And the Lord will guide you continually and satisfy your soul. You shall be like a watered garden and like a spring whose waters fail not. And if the enemy shall come in like a flood, the spirit of the Lord will lift up a defense against him. ”.  Jesus repetead many times: Love your enemies, do good to those who hate you, bless those who curse you, and pray for those who despitefully use you.  Prayer may be an angry cry for vengeance or a merciful intercession for one’s enemies. 
Said Jesus: “When an enemy smites you on one cheek, do not stand there dumb and passive but in positive attitude turn the other; that is, do the best thing possible actively to lead your brother in error away from the evil paths into the better ways of righteous living.”.  The wise man is a noble soul who is friendly in the midst of his enemies, tranquil among the turbulent, and generous among the grasping.