The traditional English hymn, God Rest Ye Merry Gentlemen , was called 'the most popular of Christmas carols' by A.H. Bullen. It first played in the United States in its best-known modern form, from an early 19th century London broadside, followed by a more popular Victorian melody, from Sandys' collection. When this coral first started is unknown.
Carols have an interesting history.
The carol's roots came not from the organized church, but from the common people who wished to express their simple ideas and honest feelings that were not expressed by the somber music of the church. By the 14th century, carol singing was firmly established throughout Europe, not to mention the dancing that accompanied it. Carols originally were association with dancing, which explains why their tunes are livelier than that of standard church music of the day. Originally, carols were sung for all occasions, not just Christmas. Carols became extremely popular by the 16th century, the century of the reformation.