Jesus commanded his followers to show self - sacrificing love toward one another. That love would be their identifying mark.
بِهٰذَا يَعْرِفُ ٱلْجَمِيعُ أَنَّكُمْ تَلَامِيذِي ،‏ إِنْ كَانَ لَكُمْ مَحَبَّةٌ بَعْضًا لِبَعْضٍ » .‏