After studying theology for several semesters, he became church musician (Kantor) in Steinau, part of the Duchy of Oppeln.
Janus worked as the music director for two churches in Sorau in Lower Lusatia, probably supported by Freiherr Sigismund Seifried von Promnitz.
Janus found a position as church musician in the duchy of Ohlau, where Luise of Anhalt-Dessau resided.
Several songs became well-known, for example "Du großer Schmerzensmann" on a text by Adam Thebesius [de], which is part of the current Protestant hymnal Evangelisches Gesangbuch as EG 87.
[3] Johann Sebastian Bach used two stanzas of this hymn, with the "Werde munter, mein Gemüte" hymn tune, to close the two parts of his cantata Herz und Mund und Tat und Leben, BWV 147: for Part I the sixth stanza, "Wohl mir, daß ich Jesum habe" and for Part II the 16th stanza, "Jesus bleibet meine Freude".