For Christians cannot be distinguished from the rest of the human race by country or language or customs. They do not live in cities of their own; they do not use a peculiar form of speech; they do not follow an eccentric manner of life...Yet, although they live in Greek and barbarians cities alike, as each man's lot has been cast, and follow the customs of the country in clothing and food and other matters of daily living, at the same time they give proof of the remarkable and admittedly extraordinary constitution of their own commonwealth. They live in their own countries, but only as aliens. They have a share in everything as citizens, and endure everything as foreigners. Every foreign land is their fatherland, and yet for them every fatherland is a foreign land.
from the anonymous Letter to Diognetus
2nd or 3rd century A.D.