Konradt, Matthias. "Chapter Twelve: The Love Command in Matthew, James, and the Didache." in Van de Sandt, Huub & Zangenberg, Jürgen K. (editors). Matthew, James, and Didache: Three Related Documents in their Jewish and Christian Settings." Atlanta, GA: Society of Biblical Literature, 2008, 271-288.
Konradt notes that the command to love is such a common trait of Christianity that an evaluation of it in Matthew, James, and the Didache would seem unlikely to yield any useful results (Konradt 2008, 271). Yet he proceeds to highlight some of the similarities before showing the marks which make the three documents fit the same milieu (Konradt 2008, 272).
Matthew uses the command to love the neighbor specifically three times (Konradt 2008, 272). Loving the neighbor, or, for that matter, loving the enemy, sets people up to be sons of God (Konradt 2008, 273). Love for the neighbor, in Matthew 19:20-21, involves giving to the poor (Konradt 2008, 275). Love for the neighbor is seen as the means of fulfilling the Law (Konradt 2008, 278).
James makes it clear that the love command is highly important. However, Konradt observes the function of that command is a matter of dispute (Konradt 2008, 278). He takes it to be intended as the command which sums up everything else and holds an ethical life together. Love is not held in the abstract in James. In 2:13 love results in showing mercy to the poor, particularly orphans and widows. Konradt notes this is not merely giving alms, but also showing respect (Konradt 2008, 279). The law does not consist of love. In fact, it goes much farther because that love is to be worked out in our various interactions with others (Konradt 2008, 281).
The Didache opens the "Way of Life" with the love command and a negative version of the Golden Rule (Konradt 2008, 282). Konradt notes that the two elements also seem to summarize the law in Matthew (Konradt 2008, 283). The similarities of James and the Didache are less clear. Perfection in the Didache is related to a love for the neighbor, but also the enemy, and to turning the other cheek (Konradt 2008, 285). It may also be tied to keeping the whole Torah, though that may not be as clearly discerned (Konradt 2008, 285-286).
Konradt finally asks whether the three documents represent the same branch of Christianity. The use of the love command is a common element which regularly shows continuity with an interpretation of the Torah (Konradt 2008, 286). The love command is seen in all as central to the law, but not as a reduction of the law. Rather, it motivates ethical behavior and attitudes which are consonant with the law.