Ignatius of Antioch, Epistle to the Magnesians 2.4
So it is fitting not only to be called Christians, but actually to be Christians. In the same way, some people call a man bishop, yet do everything apart from him. Such people do not seem to me to have a good conscience, because they do not assemble faithfully according to the commandment.
Greek
Πρέπον οὖν ἐστιν μὴ μόνον καλεῖσθαι Χρις τιανούς, ἀλλὰ καὶ εἶναι: ὥσπερ καί τινες ἐπίσκοπον μὲν καλοῦσιν, χωρὶς δὲ αὐτοῦ πάντα πράσσουσιν. οἱ τοιοῦτοι δὲ οὐκ εὐσυνείδητοί μοι εἶναι φαίνονται διὰ τὸ μὴ βεβαίως κατ’ ἐντολὴν συναθροίζεσθαι.