Unless otherwise stated, all citations taken from Roberts, A., Donaldson, J., & Coxe, A. C. (Eds.). (1885). The Epistle of Mathetes to Diognetus. In The Apostolic Fathers with Justin Martyr and Irenaeus (Vol. 1). Buffalo, NY: Christian Literature Company.
The epistle to Diognetus (pronounced Die-og-KNEE-tus) is also called the Epistle of Mathetes (Greek for “disciple” or “learner”). Chapters 1-10 serve as an early defense of the Christian faith, while chapters 11-12 are an early Christian sermon.
We only had one manuscript of this letter, which was burned in a fire during the Franco-Prussian War in 1870. Before it was destroyed, scholars made three copies—two of which have survived.
The author is not named in the letter. He calls himself a “disciple of the apostles” and “a teacher of the Gentiles” (ch.11). The author argues against Judaism (3.1-4.6), so he might not be ethnically Jewish (?).
Codex Argentoratensis Graecus ix claims that Justin Martyr was the author. Jefford notes that the style of chapters 1-10 is somewhat similar to Justin, but it could also be written by his Justin’s mentor: Tatian. Various people have been suggested as the author. We are simply not sure who wrote it. Jefford concludes, “Ultimately, it is impossible to identify with confidence any specific author(s) behind the text.”
It’s hard to date this letter because we don’t know the author. Scholars date it anywhere from AD 117-310. Jefford is inclined to date it to the end of the second century AD. He gives four reasons why: (1) It doesn’t mention the Holy Spirit, which was common for this era. (2) The author doesn’t grapple with the Trinity, which became a popular topic in the third century. (3) The author writes an apologetic against Judaism, which was less popular in the third century. (4) The letter has a universal scope in mind, which implies that the church wasn’t localized.
None of these points are conclusive for dating, but Jefford argues that their cumulative strength points to dating the letter to the end of the second century.
Important content in this letter
(Chapter 1) Diognetus receives the same title as “Theophilus” in Luke-Acts. The author calls him “most excellent Diognetus.” The author is happy to see that Diognetus is investigating Christianity, as it sets itself apart from Paganism and Judaism.
(Chapter 2) Diognetus seems to be a Pagan. The author argues against idol worship. Similar to Isaiah 40-48, he argues that idols are deaf, dumb, and blind—made out of ordinary materials.
(Chapter 3) He argues against Judaism, and their sacrifices which they offer. He even refers to “blood” sacrifices. He argues that God doesn’t need these sacrifices.
(Chapter 4) He argues against the Sabbaths, religious festivals, and ritual worship of Judaism.
(Chapter 5) He argues in favor of Christianity by pointing out that Christians love their country, but they are citizens of heaven: “They pass their days on earth, but they are citizens of heaven.” A few points are worthy of mention:
“They do not destroy their offspring.”
“They have a common table, but not a common bed.”
“They obey the prescribed laws, and at the same time surpass the laws by their lives. They love all men, and are persecuted by all. They are unknown and condemned; they are put to death, and restored to life.”
“Those who hate them are unable to assign any reason for their hatred.”
(Chapter 6) “To sum up all in one word—what the soul is in the body, that are Christians in the world.”
(Chapter 7) He teaches the deity of Christ: “As a king sends his son, who is also a king, so sent He Him; as God He sent Him; as to men He sent Him; as a Saviour He sent Him, and as seeking to persuade, not to compel us; for violence has no place in the character of God.”
He refers to Christian persecution: “Do you not see them exposed to wild beasts, that they may be persuaded to deny the Lord, and yet not overcome? Do you not see that the more of them are punished, the greater becomes the number of the rest? This does not seem to be the work of man: this is the power of God; these are the evidences of His manifestation.”
(Chapter 8) He argues against the philosophers who say that God is in the elements of nature (e.g. fire, water, etc.).
(Chapter 9) He teaches substitutionary atonement: “He Himself took on Him the burden of our iniquities, He gave His own Son as a ransom for us, the holy One for transgressors, the blameless One for the wicked, the righteous One for the unrighteous, the incorruptible One for the corruptible, the immortal One for them that are mortal. For what other thing was capable of covering our sins than His righteousness? By what other one was it possible that we, the wicked and ungodly, could be justified, than by the only Son of God? O sweet exchange! O unsearchable operation! O benefits surpassing all expectation! that the wickedness of many should be hid in a single righteous One, and that the righteousness of One should justify many transgressors!”
(Chapter 10) Diognetus is not a Christian yet: “If you also desire [to possess] this faith, you likewise shall receive first of all the knowledge of the Father.”
(Chapter 12) He references the “tree of paradise,” alluding to Genesis 2-3.
 Jefford, C. N. (2012). Reading the Apostolic Fathers: A Student’s Introduction (Second Edition, p. 166). Grand Rapids, MI: Baker Academic.
 Jefford, C. N. (2012). Reading the Apostolic Fathers: A Student’s Introduction (Second Edition, p. 167). Grand Rapids, MI: Baker Academic.
 Jefford, C. N. (2012). Reading the Apostolic Fathers: A Student’s Introduction (Second Edition, p. 168). Grand Rapids, MI: Baker Academic.
 Jefford, C. N. (2012). Reading the Apostolic Fathers: A Student’s Introduction (Second Edition, p. 168-169). Grand Rapids, MI: Baker Academic.