The Epistle of Mathetes to Diognetus is probably the earliest example of Christian apologetics, writings defending Christianity from its accusers. The Greek writer and recipient are not otherwise known, but the language and other textual evidence dates the work to the late 2nd century; some assume an even earlier date and count it among the Apostolic Fathers. "Mathetes" is not a proper name; it simply means "a disciple." A Diognetus was a tutor of the emperor Marcus Aurelius, who admired him for his freedom from superstition and sound educational advice (Meditations 1.6), but he is not likely to be the recipient, or even the assumed recipient, of this apology.
The writer is a Johannine Christian who does not use the name "Jesus" or the expression the "Christ" but prefers the use of "the Word."
The Epistle survives in two manuscripts. A third, that survived until 1870, was in a 13th century codex that included writings ascribed to Justin Martyr. The other two are probably copied from this. It was at Strasbourg but was burned there during the Franco-Prussian War. Fortunately it had already been printed, the first time in 1592, when it was generally ascribed to Justin Martyr because of the context of its manuscript. In all manuscripts, about two lines of the text are missing in the middle. The 13th century manuscript was obviously damaged in that place and the copies were made only after that damage had already been done.
The Epistle is in twelve chapters.
The 10th chapter breaks off in mid thought, and so the following two chapters, a kind of peroration that abandons the (fictive ?) epistolary formula, are often considered to be later additions, for characteristically 3rd-century contentions appear in them: "This Word, Who was from the beginning...". Some have ascribed these additions to Hippolytus, based on similarities of thought and style. In the 11th chapter "Mathetes" presents himself as "having been a disciple of Apostles I come forward as a teacher of the Gentiles, ministering worthily to them" placing himself in a class with authoritative figures like John the Presbyter.
Chap. XI. — These Things Are Worthy to Be Known and Believed.
I do not speak of things strange to me, nor do I aim at anything inconsistent with right reason; but having been a disciple of the Apostles, I am become a teacher of the Gentiles. I minister the things delivered to me to those that are disciples worthy of the truth. For who that is rightly taught and begotten by the loving Word, would not seek to learn accurately the things which have been clearly shown by the Word to His disciples, to whom the Word being manifested has revealed them, speaking plainly [to them], not understood indeed by the unbelieving, but conversing with the disciples, who, being esteemed faithful by Him, acquired a knowledge of the mysteries of the Father? For which reason He sent the Word, that He might be manifested to the world; and He, being despised by the people [of the Jews], was, when preached by the Apostles, believed on by the Gentiles. ([Comp. 1Ti_3:16.]) This is He who was from the beginning, who appeared as if new, and was found old, and yet who is ever born afresh in the hearts of the saints. This is He who, being from everlasting, is to-day called the Son; through whom the Church is enriched, and grace, widely spread, increases in the saints. furnishing understanding, revealing mysteries, announcing times, rejoicing over the faithful. giving to those that seek, by whom the limits of faith are not broken through, nor the boundaries set by the fathers passed over. Then the fear of the law is chanted, and the grace of the prophets is known, and the faith of the gospels is established, and the tradition of the Apostles is preserved, and the grace of the Church exults; which grace if you grieve not, you shall know those things which the Word teaches, by whom He wills, and when He pleases. For whatever things we are moved to utter by the will of the Word commanding us, we communicate to you with pains, and from a love of the things that have been revealed to us.
Lona, Horacio E.: "An Diognet", Übersetzt und erklärt, ed. by N. Brox, K. Niederwimmer, H. E. Lona, F. R. Prostmeier, and J. Ulrich. (Series: Kommentar zu frühchristlichen Apologeten, KfA, Vol. 8). Verlag Herder: Freiburg u.a., 2001. ISBN 3-451-27679-8