For generations, Christmas carols were sung by the world everywhere during the holiday season. It was a traditional past time to gather around and regal others with songs and poems.
The Christian orders of the day demanded the hymns be sung to propagate Trinitarian Christian doctrine claiming that God the Father, Jesus the Son, and the Holy Spirit are all equals, three beings in separate forms. Arianism, on the other hand, claimed that Jesus was deistically lower than God was, because He was created afterwards in human form.
The songs of ancient times were in Latin, the scholarly language of the day, and as such, were immensely unpopular.