"For Christians are not distinguished from the rest of humanity by country, language, or custom. 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. This teaching of theirs has not been discovered by the thought and reflection of ingenious people, nor do they promote any human doctrine, as some do.
"But 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. They live in their own countries, but only as non-residents; they participate in everything as citizens, and endure everything as foreigners. Every foreign country is their fatherland, and ever fatherland is foreign.
"They 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. They obey the established laws; indeed in their private lives they transcend the laws. They love everyone, and by everyone they are persecuted."Selection from The Letter of Diognetus (2nd century A.D.)