This epistle is from some time in the second century. Diognetus was a tutor of Emperor Marcus Aurelius. Mathetes is Greek for student or disciple, so it’s not a proper name. The letter was discovered in the 13th century in a codex with letters from Justin Martyr. Justin Marty living around this time and writing similar apologetic letters to the Roman authorities makes Justin a possible candidates of the letter. In the letter he claims to be a disciple of the Apostles, which would make Justin Martyr an unlikely candidate.

Either way, the letter indicates that Diognetus was interested in learning more about the Christians. And this letter is a defense and description of Christianity and Christ Himself. It’s a fairly basic defense. Christians find idols to be vanity and false worship. Christians aren’t superstitious like the Jews. He compares the worship of the Jews to pagan idolatry. That the God who created everything is in need of nothing, he says. He is highly critical of the Jews, calling their worship madness and folly.

He describes Christians as other worldly, but also good citizens. That they don’t wear distinct clothes or eat different food from the natives of their respective cities, whether they be in Greek or barbarian cities. But that their moral character is different. They marry and have children, but they don’t destroy their offspring. They have a common table, but not a common bed. They are in the flesh, but they don’t live after the flesh. They obey the prescribed laws, and yet surpass the laws by their lives. They love all men, and are persecuted by all. He describes Christians as the soul of the world.

He defends the reality of Christ and explains why he came. Though he never uses the name Christ or Jesus. He always refers to Christ as The Word. In one chapter he explains the timing of Christ’s manifestation. And what’s interesting is that he puts forward the doctrine of substitutionary atonement. It is often said by Romanists and Eastern Christians that substitutionary atonement was a Protestant invention, but here it appears the Disciple is teaching this very thing.

“But when our wickedness had reached its height, and it had been clearly shown that its reward, punishment and death, was impending over us; and when the time had come which God had before appointed for manifesting His own kindness and power, how the one love of God, through exceeding regard for men, did not regard us with hatred, nor thrust us away, nor remember our iniquity against us, but showed great long-suffering, and bore with us, 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!” – Ch. IX WHY THE SON WAS SENT SO LATE