Christmas hymns for centuries had only been sung in church, and then, only in Latin. And because few people regularly spoke Latin, the songs never really made it outside the religious world.
Only recently have Christmas hymns been sung in native languages around the world.
In fact, although the earliest Christmas songs date from the fourth century, it wasn't until the Protestant era that the change began to take place.
And when the festive carols began to be incorporated into the local celebrations, they were initially frowned upon by some members of the church.
Perhaps the most famous of all Christmas carols, "Silent Night," was written in Austria in the early 19th century.
In the times since, Christmas carols largely have become more popular, joyous tunes, incorporating both the religious and secular themes of Christmas.