Harnack, Adolf. “Prolegomena, § 2. Der Title, die Adresse und der Zweck der Schrift” Lehre der Zwölf Apostel. Leipzig, J.C. Hinrichs, 1884, pp. 24-37.
Harnack observes the dual titles of the Didache, noting that early references to the text make mention of both titles. He considers that the longer title was certainly the older (Harnack 1884, 24). His reasoning is that a longer title is easily shortened in common usage, but a short title is very unlikely to be lengthened (Harnack 1884, 25). He further considers that Papias appeared to think the text had apostolic origin. Because of Papias’ time, writing in the early 2nd century and having contact with at least the generation immediately after the 12 apostles, Harnack thinks Papias’ sense of the matter is reliable (Harnack 1884, 26). Justinian also took the text to originate with the apostles. Harnack also makes an argument from silence, that he finds no subsequent writings that claim authorship by the 12 apostles. He then goes so far as to suggest that Acts 2:42, and possibly also Acts 13:12, 1 Cor. 14:6, Tit. 1:9, and 2 John 9-10 make reference to this work.There may also be hints of the Didache in Barnabas 16:9 and in Justin Apol. 1:4 (Harnack 1884, 27).
The address “to the Gentiles” is a further challenge. Harnack finds the sharp distinction between Jew andGentile to be a feature of the earliest period of Christianity, almost entirely passing away by about the third generation of Christians (Harnack 1884, 28). The apparent use of the text for catechesis of adult converts also seems to indicate a setting in which Christianity had not spread very widely. Again, this points to an early date. The Christian culture does not seem established to the point of being common knowledge to the original audience (Harnack 1884, 29).
Harnack concludes that the purpose of the Didache is catechetical, which classifies it in genre with James, Jude, 1 &2 Peter, Hebrews, and the letter of Barnabas (Harnack 1884, 30). It addresses Gentiles, not mentioning Jews until chapter 8, and there suggesting they are”hypocrites.” The question may well arise whether there was a sharp distinction between Jewish and Gentile Christianity at the time. The fact that the Didache is written “for the Gentiles” suggests so, but not necessarily with an implication of conflict. The Gentile converts would reasonably be assumed to need a different level of catechesis than would Jewish converts (Harnack 1884, 31). The goal of catechesis is that Christians can live a faithful life in their society. Harnack, particularly citing the Younger Pliny’s misunderstanding of Christianity, acknowledges that there would be a significant understanding gap between Christianity and the pagan culture (Harnack 1884, 32). The challenge was to communicate what Christians need to know in brief terms. Harnack sees this as a challenge especially in the light of the rising Gnosticism, which would reinterpret statements to make them fit its own philosophies (Harnack 1884, 34). For this reason it was very important to reinforce the apostolic teaching. Harnack notes especially the Trinitarian nature of the Didache, the emphasis on the Sacraments, and the idea of Jesus as the fulfillment of the promise to David as ways it reinforces apostolic teaching (Harnack 1884, 36).