Interestingly, the Society quotes from the Letter to Diognetus to support their belief that Christians are to be "no part of the world," yet carefully excise any hint that the illustration used in the letter assumes a notion of an immortal soul.
*** w51 3/1 pp. 139-140 Early Christians Under Roman Rule ***Some historians have debated over why God’s people were singled out and persecuted beyond measure, but when one sees the issue it is quite simple to understand. A letter addressed to Diognetus, who lived in the early part of the second century, says: "The Christians are not separated from other men, either in their earthly abode, nor by language, nor customs; they never inhabit separate towns, they use no peculiar speech, no singular mode of life.—They dwell in the towns of Greeks, or of Barbarians, just as chance has assigned their abode and inasmuch as they follow the customs of the country with regard to raiment, food, and other such matters, they show a temper and conduct which is wonderful and remarkable to all men. They obey the existing laws, nay, they triumph over the laws by their own conduct."
*** w93 7/1 p. 14 Christians and Human Society Today ***
Most of the Roman emperors misunderstood the early Christians and persecuted them. Showing why, The Epistle to Diognetus, thought by some to date from the second century C.E., declares: "Christians dwell in the world, but are not part and parcel of the world."
Here is the full quote:
"The Christians are not separated from other men, either in their earthly abode, nor by language, nor customs; they never inhabit separate towns, they use no peculiar speech, no singular mode of life. They dwell in the towns of Greeks, or of Barbarians, just as chance has assigned their abode and inasmuch as they follow the customs of the country with regard to raiment, food, and other such matters, they show a temper and conduct which is wonderful and remarkable to all men. They obey the existing laws, nay, they triumph over the laws by their own conduct....In a word, what the soul is in a body, this the Christians are in the world. The soul is spread through all the members of the body, and Christians through the divers cities of the world. The soul has its abode in the body, and yet it is not of the body. So Christians dwell in the world, and yet they are not part of the world. The soul which is invisible is contained in the body which is visible, so Christians are recognised as being in the world, and yet their religion remains invisible. The flesh hates the soul and wages war with it, though it receives no wrong, because it is forbidden to indulge in pleasures; so the world hates Christians, though it receives no wrong from them, because they set themselves against its pleasures. The soul loves the flesh which hates it, and its body parts, so Christians love those that hate them. The soul is enclosed in the body, and yet itself holds the body together; so Christians are kept in the world as in a prison-house, and yet they themselves hold the world together. The soul though itself immortal dwelleth in a mortal tabernacle; so Christians sojourn amidst perishable things, while they look for the imperishability which is in the heavens. The soul when hardly treated in the matter of meats and drinks is improved; and so Christians when punished increase more and more daily" (Epistle to Diognetus 5:1-5, 6:1-9).