For Christians are not distinguished from the rest of humanity by country, language, or custom. 2 For nowhere do they live in cities of their own, nor do they speak some unusual dialect, nor do they practice an eccentric way of life…4For while they live in both Greek and barbarian cities, as each one’s lot was cast, and follow the local customs in dress and food and other aspects of life, at the same time they demonstrate the remarkable and admittedly unusual character of their own citizenship. 5The live in their own countries but only as nonresidents, they participate in everything as citizens, and endure everything as foreigners. Every foreign country is their fatherland, and every fatherland is foreign. 7They marry like everyone else, and have children, but they do not expose their offspring. They share their food but not their wives. They are in the flesh, but they do not live according to the flesh. They live on earth but their citizenship is in heaven. 10They obey the established laws; indeed in their private lives they transcend the laws. 11They love everyone, and by everyone they are persecuted.
Epistle to Diognetus (c. 150 AD), 5.1–11.