This is one of the earliest forms of Christian apologetics, save for the Gospels and Acts, and is relatively newly in the hands of readers. The Greek writing known under this name was first printed in 1592 by Henricus Stephanus, along with a companion piece To Greeks, as hitherto unknown writings of Justin Martyr, taken by him from a single faded exemplar. The initial date of composition is unknown, but by using internals to judge, it seems that it was written in the early 2nd century, some give the date as around 125ad. The Diognetus to whom it is addressed is unknown, though some scholars have sought to identify him with a Diognetus who was a teacher of Marcus Aurelius.
From Kirsopp Lake in The Apostolic Fathers (published London 1912), v. II, pp. 348-349:
Like most early apologies for Christianity it begins by expounding the foolishness of the worship of idols, and the inadequacy of the Jewish religion and then proceeds to give a short sketch of Christian belief, a panegyric on Christian character and a description of the benefit which it offers to converts. In this respect it resembles the apology of Aristides, and somewhat less closely those of Justin and Tatian, and the suggestion has been made that it may have been written by Aristides. Its style is, however, rhetorical in the extreme and it may be doubted whether it was not an academic treatise or possibly the exercise of some young theologian rather than an actual apology sent to a living person. The general impression made by the document is unfavourable to any theory of an early date and quite decisive against the tradition which seems to have been preserved in the lost MS. in which the epistle was found, attributing it to Justin Martyr. Harnack thinks that it more probably belongs to the third than to the second century, but early tradition does not mention the epistle and there is nothing in the internal evidence to justify any certainty of opinion.
It is perhaps one of the most simplistic objects of beauty written during that time period. It was well preserved by ancient hands that might, just as they have done with other writings from the Early Church Fathers, attempt to inflate, add, or otherwise change the original letter. It was is straight forward, without much deep theology, but attempts to lay open the entire Christian experience. One can easily imagine what the original questions were that prompted this letter.
It has to be remembered that Rome respected only the ancient, and thus gave some passes to the Jewish religion that it did not afford to the ‘new’ Christian ‘superstition’, but the writer of this letter stresses the length of Christianity, as well as the breadth while giving an excellent understanding of the Christian of the 2nd century world.
Below is Chapter 5 from Lightfoot’s translation:
5:1 For Christians are not distinguished from the rest of mankind either in locality or in speech or in customs.
5:2 For they dwell not somewhere in cities of their own, neither do they use some different language, nor practice an extraordinary kind of life.
5:3 Nor again do they possess any invention discovered by any intelligence or study of ingenious men, nor are they masters of any human dogma as some are.
5:4 But while they dwell in cities of Greeks and barbarians as the lot of each is cast, and follow the native customs in dress and food and the other arrangements of life, yet the constitution of their own citizenship, which they set forth, is marvelous, and confessedly contradicts expectation.
5:5 They dwell in their own countries, but only as sojourners; they bear their share in all things as citizens, and they endure all hardships as strangers. Every foreign country is a fatherland to them, and every fatherland is foreign.
5:6 They marry like all other men and they beget children; but they do not cast away their offspring.
5:7 They have their meals in common, but not their wives.
5:8 They find themselves in the flesh, and yet they live not after the flesh.
5:9 Their existence is on earth, but their citizenship is in heaven.
5:10 They obey the established laws, and they surpass the laws in their own lives.
5:11 They love all men, and they are persecuted by all.
5:12 They are ignored, and yet they are condemned. They are put to death, and yet they are endued with life.
5:13 They are in beggary, and yet they make many rich. They are in want of all things, and yet they abound in all things.
5:14 They are dishonoured, and yet they are glorified in their dishonour. They are evil spoken of, and yet they are vindicated.
5:15 They are reviled, and they bless; they are insulted, and they respect.
5:16 Doing good they are punished as evil-doers; being punished they rejoice, as if they were thereby quickened by life.
5:17 War is waged against them as aliens by the Jews, and persecution is carried on against them by the Greeks, and yet those that hate them cannot tell the reason of their hostility.
6:1 In a word, what the soul is in a body, this the Christians are in the world.
It should be so today, but too many people desire the attention of the world, or to fit in. If it not our place to exercise our godliness in the public arena, whether it is oratory skills or other such talents that God has given us for the benefit of His kingdom. There are times that we must use those things which God has bestowed upon us, but if the talent is reserved for His kingdom, then we should have enough of the Spirit in us to keep us from using them for the glory of humanity.
We read in this above letter that the Christians are in this world but not of this world and although we dwell in the cities, our citizenship does not belong there.
We should question ourselves daily on those things that might lead others away from Christ. How can we joyfully prostitute our talents out to the world when they should be reserve solely for God? Do we sing by talent? Then sing on the songs of Zion? Are we of the intellectual variety? Then let us give full heed to teaching the congregation of God so that no false doctrine may enter in. We woke up one day, at some altar, to find that we were in the flesh, but let us live instead after the Spirit. If we find ourselves lonely or poor, let us remember that it is the name of Christ that has given us riches abounding more and more every day.
Our time on earth is short, and the path narrow, but if we pay heed to Christ and not follow after the world, then we will find the abundance of grace that is in God and dwell with Him forever.