The Catholic Church valued music greatly and it is no wonder that the early Christmas songs date from 4th century (the earliest known is Jesus refulsit omnium by St.Hilary of Poitiers). The Mediaeval Christmas music followed the Gregorian tradition. In Renaissance Italy there emerged a lighter and more joyous kind of Christmas songs, more like the true carols (from the French word caroler, meaning to dance in a ring). These songs continued to be religious and in Latin, though. In Protestant countries the tradition, as everything Christmas related, intensified.Ayers Rock
Luther wrote and composed his song "From Heaven above I come to You". Music by Handel and Mendelssohn was adapted and used as Christmas carols. The old Finnish/Swedish collection Piae Cantiones was translated and published in English in mid - 19th century. The most famous of all, Silent Night (Stille Nacht, heilige Nacht) was written by the Austrian parish priest Joseph Mohr and composed by Franz Gruber, church organist, in 1818. In 19th century and later many popular songs were written by composers (e.g. Adam, Sibelius). The themes of songs surpassed religion and the totality of Christmas paraphernalia found its way to carol music.