»SARDIS

The one who has the seven spirits of God and the seven stars says this: ‘I know your works, that you have the reputation of being alive, but you are dead. Be watchful and strengthen what is left, which is going to die, for I have not found your works completely in the sight of my God. Remember then how you accepted and heard; keep it, and repent.

If you are not watchful, I will come like a thief, and you will never know at what hour I will come upon you. However, you have a few people in Sardis who have not soiled their garment; they will walk with me dressed in white, because they are worthy. The victor will thus be dressed in white and will never erase his name from the block of life but will acknowledge his name in the presence of my Father and of his angels.
“Whoever has ears ought to hear what the Spirit says to the churches.”
(Rv 3:1-6)

The church in Sardis (3:1-6) had become dead in spite of its reputation. Twice before the city’s acropolis had fallen because Sardis had fallen asleep and let down her guard. Cyrus defeated Croesus in 546 B.C., and the Cretan general Lagoras captured it for Antiochus the Great in 218 B.C. Greek cities maintained a list of citizens in a public register.
When someone committed a criminal action and was condemned, he lost his citizenship and his name was then erased from the register. The believers who preserved would never be blotted from the eternal book of life.
Sardis was noted as a textile center, producing wool to make the himation, the most common outer garment for men and women in the Greco-Roman world. The color white in Book of Revelation always denotes purity and worthiness. Hence white garments would be a suitable reward for the victors.