Enemy: one that is antagonistic to another, especially : one seeking to injure, overthrow, or confound an opponent.*
Being nice to everybody, especially with those whom I disagree, is not the measure of Christian discipleship. The law of love is, according to Jesus, measured by my treatment of my enemies. If growing in love is the point, it has to be more than being nice, whether it's returned or met with a scowl.
But there is even a deeper root of enemy- love that' forms the core of my discipleship: given the fact that real enemies do exist, i.e., those who plot, speak, or act in harmful ways, I am asked, required, taught, to love and pray for them.
I will long remember the wisdom learned in a covenant group where we agreed to pray for our enemies daily. Praying for my enemies on a daily basis restrained me from harmful behaviors that would have certainly made a difficult situation worse. This practice helped me survive, ethically and spiritually, one of the more challenging seasons in my life and ministry.
Inevitably, praying for my enemy is not magic; it's hard spiritual work. It's repentance from enacting harm and plotting self-vindication. From making a bad situation worse. Yet, I cannot think of a more non-violent way of resisting evil as a Christ-follower than to pray for my foes as well as my friends.
Nice-ness pretends there are no enemies and shrivels in face of evil. Nice-ness also excuses me of my complicity in stoking the fires of hate and harm. What about the faith of Jesus Christ? In the end, while pleasantness is helpful to get along, nice-ness is not necessarily a mark of growing in love.
**The word "restraint" is named as a work of the Holy Spirit in the classic baptismal prayer (UMC). The pastor prays to God, for the newly baptized infant, that, "by the restraining and renewing influence of the Holy Spirit, she may always be a true child of yours, serving you faithfully all the days of her life."