God Rest Ye Merry, Gentlemen is an old English Christmas carol whose composer is unknown. The song was published in 1833 by William B. Sandys. The poem 'I Heard the Bells on Christmas Day' by Henry Wadsworth Longfellow is based on this carol. The carol tells the story of the birth of Jesus Christ and how he came to save humanity from Satan's power. The carol is a celebration of the joy and comfort that the birth of Jesus brings to the world.