Listen to Mass in C major, K.257 "Credo-Messe": Agnus Dei online. Mass in C major, K.257 "Credo-Messe": Agnus Dei is an Unknown language song and is sung by Peter Neumann/Collegium Cartusianum Köln/Kölner Kammerchor/Ann Monoyios/Elisabeth Graf/Oly Pfaff/Franz-Josef Selig. Mass in C major, K.257 "Credo-Messe": Agnus Dei, from the album Mozart: Sämtliche Messen / Complete Masses, was released in the year 2011. The duration of the song is 5:34. Download Unknown songs online from JioSaavn.