But scripture tells us to bless our enemies, bless those who persecute us and pray for them and so on. And although I believe the Good Samaritan is a parable and not a real story it doesn't make any difference, because the idea is that the Samaritan took care of a Jew who was his enemy. Of course, assuming you are a true Christian you are my brother in a sense an unbeliever isn't, but I don't think that's what is meant here. But I don't want to get into a theological argument about this.
He who surrenders the first page of his Bible surrenders all. --John William Burgon, Inspiration and Interpretation, Sermon II.