The Epistle to Diognetus is particularly interesting amongst the apostolic literature which it is traditionally included with in that along with the Fragments of Quadratus, it is not written to other Christians, but rather to non-believers. The epistle is an apologetic work which aims to defend Christianity to outsiders. During the second century CE, Christianity was growing at a significant pace, and was no longer able to remain largely unnoticed within wider Greco-Roman culture. Rumours about this strange “superstition” (see Tacitus, Annals XV.44 for the famous identification of Christianity as a “mischievous superstition”) began to spread, and the Christians found themselves accused of acts such as cannibalism (stemming from the “body” and “blood” of Christ consumed at the Eucharistic meal) and infant sacrifice. Their shunning of traditional gods was also met with charges of atheism (see, for example, Celsus, On the True Doctrine, written around 178 CE, but which we know primarily through Origen’s Against Celsus. Celsus criticises Christian beliefs at length as a complete perversion of traditional, ancestral values, foolishly advocating blind faith over reason). In response to such attacks, Christian apologists of the second century CE (such as Justin Martyr, Athenagoras, and Theophilus of Antioch to name a few examples) sought to counter such rumours by explaining Christian doctrine and rituals, and appealing to their ancient origins on account of the fact that they grew out of Judaism – Christianity was commonly denigrated (e.g. by Celsus) for being a new belief system with no established heritage. Moreover, several writers sought to minimise tension between Christianity and the Roman government by asserting that they were taught to remain loyal and obedient to ruling authorities (biblical support for this view is found in Romans 13:1-7 and 1 Peter 2:12-17; in addition to the apologists, we find this view expressed, for instance, in 1 Clement 60.4-61.3 and the Martyrdom of Polycarp 10.2).

The author of the epistle is anonymous, and it is uncertain whether the Diognetus to whom the letter is addressed was a historical figure or simply an imagined recipient. Moreover, the date of the letter is very uncertain, and it is missing its ending (Henry Meechum, The Epistle to Diognetus, p. 19, and William Frend, The Rise of Christianity, p. 236, argue for a date around 150 CE, but Robert Grant, Greek Apologists, p. 178-179, believes it to be later, closer to 225 CE). While various suggestions have been made regarding authorship (e.g. that it was Polycarp of Smyrna – Charles Hill, From the Lost Teaching of Polycarp, Hippolytus of Rome, or Theophilus of Antioch), evidence is not strong – there are no particular stylistic similarities between the epistle and the works of such authors, for example (see Michael Holmes, Apostolic Fathers, p. 688). The author’s main purpose is to address three particular questions, which he outlines in section 1: 1) Who is the God that Christians believe in and how do they worship him? 2) What is the precise nature of the heartfelt love that Christians express for one another? 3) Why has this new “race” (γένος) only appeared now and not earlier? In the present passage, the author sets out to explain that while Christians are different in several ways from their non-Christian neighbours, they are capable of residing and integrating into any community. Particularly interesting are the author’s assertions about Christian “citizenship” (πολιτεία) which when read in light of Paul’s discussion πολίτευμα in Philippians 3:18-21 (clearly the author’s inspiration here), appears to reveal an early-Christian attempt to minimise cultural tension between Christians and the wider Greco-Roman world which they inhabited by drawing on the language of regional identity and belonging.

The author argues that the Christians are different from the rest of humanity in that they do not share a specific language or come from one geographical region. They do not live in particular places, rather inhabiting both Greek and barbarian cities “as each one’s lot was cast.” Therefore, “belonging” in the sense of regional identity is for Christians entirely dependent on where they happen to be born or where, for whatever reason, they happen to be living. Christian identity crosses the boundaries of language and distance. The fact that the author describes Christians as readily following local customs in terms of food and dress serves to emphasise that they are wanting to accommodate to their surroundings and are not entirely counter-cultural. For apologists such as the present author, reducing potential tension by showing that Christians were capable of living in the wider world without causing ructions in everyday life was important. However, Christians do have a slightly unusual “citizenship” (πολιτεία) (verse 4). It is important to note that the author of the present text uses πολιτεία, whereas Paul in Philippians 3:20 uses πολίτευμα, a term which has caused much debate among commentators on Paul’s letter (see the discussion below). The author of the Epistle to Diognetus seems to have a clear idea of “citizenship” in terms of one’s belonging to a specific city in mind, especially given the discourse which immediately follows in verse 5 relating to residency, foreignness, and fatherlands. Here, three contrasts are given relating to Christian identity: 1) Christians each live in their own country (πατρίς), yet are non-residents (πάροικοι); 2) Christians are citizens (πολῖται), yet are foreigners (ξένοι) at the same time; 3) foreign countries (i.e. those where the Christian does not live) are considered fatherlands to Christians, yet every country still remains foreign. On the one hand, the author asserts that Christians are at home in any place (any country can be a fatherland for a Christian), yet on the other hand, he suggests that wherever they are, they in one sense remain as foreigners. In the author’s mind there is a difference between citizenship of whatever earthly city one happens to be from (where the Christian can and will participate in most of the local customs) and one’s citizenship in the heavenly community (verse 9). This is perhaps best understood in conversation with Philippians 3:18-21.

The author clearly draws on Paul’s claim in Philippians 3:18-21: “For many, whom I have often told you about, and now even tell you with tears, live as enemies of the cross of Christ. Their end is destruction, their god is the belly, and they glory in their shame, thinking of earthly things. But our πολίτευμα is in heaven, from where we eagerly await a Saviour, the Lord Jesus Christ, who will transform our lowly body to be like his glorious body, according to his power which enables him to subject all things to himself.” Interpreters continue to wrestle with how best to render the πολίτευμα of Philippians 3:20, often translated as “citizenship” (other suggestions include “association”, “judicial body”, “governing association” – see the commentary on this text for details), with the assumption being that Paul is simply wanting to draw a distinction between the behaviour fitting of a member of God’s heavenly ‘city’ and that of a member of an earthly city. The LSJ English-Greek Lexicon offers a variety of renderings for politeuma, including “corporate body of citizens resident in a foreign city,” “association,” and indeed “citizenship.” Essentially, Paul is contrasting the way of life in God’s heavenly kingdom with that of non-Christians who merely focus on earthly matters – despite the intense debates among scholars over the years, therefore, the general feeling of the passage seems relatively clear; the Christian community belongs to something different, and by implication better than the non-Christian community. It remains debatable whether Paul had notions of Roman citizenship or small governing political associations in mind when he wrote his letter to the Christians of Philippi (a Roman colony which had a strong bond with Rome, housing many veteran soldiers), but what seems clear is that politeuma for Paul comes with certain behavioural responsibilities. The politeuma of heaven requires active participation. The Christians must understand their identity in relation to their membership of the heavenly kingdom, and just as citizens of Rome or inhabitants of a particular town are bound by certain laws and can claim a particular spatial identity, Christ’s followers ought to act according to Christian values.

The author of the Epistle to Diognetus seems to understand citizenship in a similar way, at least theologically. Owing to his apologetic agenda, the author of the present text must balance the primary heavenly identity of the Christians with their earthly identity, which is entirely dependent on the place in which each believer happens to reside. While the phrase ‘the unusual character of their πολιτεία’ in verse 4 might be understood in general terms to refer to a ‘manner’ or ‘way’ of life, as Meechum argues, πολιτεία should be taken here as strongly indicating the notion of citizenship tied to a city or country (Epistle to Diognetus, p. 109). Indeed, when one compares the language and claims regarding citizenship in Diognetus with Greek honourific inscriptional evidence from Asia Minor, it seems likely that a city in this locale may have hosted the author (Charles Hill, From the Lost Teaching, has set out a detailed argument for Smyrna, and argues that the author was Polycarp, the famous martyr). Clayton Jefford argues that the author of the Epistle to Diognetus understands Christians to be like Paul when it comes to their ‘true citizenship’; i.e. they are born into true, heavenly citizenship when they are baptised as Christians, undergoing a rebirth which elevates them to the same level of honour as the most respected Roman citizens (Epistle to Diognetus, p. 221). However, this reads into the passage an element that is not entirely obvious. The fact that Christians are described as obeying local customs and laws suggests rather that they conform to the civic expectations of their individual cities.

The author does not distinguish between a person’s original place of birth and their current location of habitation. As verses 6, 7, and 10 explain, Christians engage in most of the same everyday practices as non-Christians, making them not dissimilar to everyone else. Granted, their moral tenets require that certain behaviours are out of the question, such as leaving unwanted children to die, or engaging in sexual promiscuity – these are the types of superior “laws” which Christians hold above those made by earthly authorities (verse 10). However, it is made clear that Christians will still uphold earthly laws, and in this sense should not be seen as challenging the governing authorities (this was a common assertion of early-Christians; see, for example, 1 Clement 60.4-61.3 and 1 Peter 2:12-17). This passage presents a notable mixture of 1) apologetic assurances that Christians are essentially capable of fitting into the fabric of any community, and as such, need not be feared or viewed suspiciously by their non-Christian neighbours, and 2) assertions of overall moral superiority on the part of the Christians. While wanting to present Christianity as accommodating and unthreatening in one sense, therefore, this message is still underpinned by a clear feeling that the Christians essentially had surpassed the world that they shared with their non-Christian neighbours, who were still bound to the flesh, and remained merely citizens of the material realm (verses 8-9).