An early Christian document known as the Epistle to Diognetus (c. A.D. 120-200) is believed to have been written by a man named Athenagoras. In one important section the author describes how Christians are alike—and different from others:

The difference between Christians and the rest of mankind is not a matter of nationality, or language, or customs. Christians do not live in separate cities of their own, speak any special dialect, not practice any eccentric way of life. … They pass their lives in whatever township—Greek or foreign—each man's lot has determined; and conform to ordinary local usage in their clothing, diet, and other habits. Nevertheless, the organization of their community does exhibit some features that are remarkable, and even surprising. For instance, though they are residents at home in their own countries, their behavior there is more like transients. … Though destiny has placed them here in the flesh, they do not live after the flesh; their days are passed on earth, but their citizenship is above in the heavens. They obey the prescribed laws, but in their own private lives they transcend the laws. They show love to all men—and all men persecute them. They are misunderstood, and condemned; yet by suffering death they are quickened into life. They are poor, yet making many rich; lacking all things, yet having all things in abundance. … They repay [curses] with blessings, and abuse with courtesy. For the good they do, they suffer stripes as evildoers.