I once asked a similar question of a very good priest. He told me that as Christians, we are obliged to love everyone. But we do not have to like them.
“Love” does not mean some type of mushy-gushy warm feeling or emotional attraction. To love one’s enemies means to consciously desire their ultimate well-being. In the case of a rapist or murderer, to pray for their conversion of heart and sincere repentence would be an act of love toward such an enemy. Although my sense of justice cries out for revenge and punishment, my sense of love asks not to avenge evil, but to convert evil to good.