добровольное служение

From LSJ

μοῦνοι Ἑλλήνων δὴ μουνομαχήσαντες τῷ Πέρσῃ → alone of all Greeks we met the Persian singlehandedly, alone of all Greeks having fought singlehanded with the Persians

Source

Russian > Greek

ἐθελοθρησκεία