Revelation 3:1-3

1“Write to the angel of the church in Sardis: Thus says the one who has the seven spirits of God and the seven stars: I know your works; you have a reputation for being alive, but you are dead.

2Be alert and strengthen what remains, which is about to die, for I have not found your works complete before my God.

3Remember, then, what you have received and heard; keep it, and repent. If you are not alert, I will come like a thief, and you have no idea at what hour I will come upon you.