Songfacts®:

• This is a traditional English carol dating back to the 16th or 17th century. It was first published in England in 1833, when it appeared in Christmas Carols Ancient and Modern, a collection of seasonal carols gathered by William B. Sandys. Ancient and Modern also marked the first publication of "The First Nowell," "I Saw Three Ships" and other great carols.
• The arrangement generally used for this carol today first appeared in the 1871 collection, Christmas Carols New and Old by Sir John Stainer and the Reverend H.R. Bramley. Apart From "God Rest You Merry Gentlemen," their compilation also included Stainer's arrangements of what were to become the standard versions of "Good King Wenceslas," "The First Nowell" and "What Child is This?" among others.
• When the character Scrooge in Charles Dickens' A Christmas Carol heard this cheerful carol, he grabbed a ruler and made the singer flee in terror.
• Bing Crosby recorded this on June 8, 1942 with John Scott Trotter and His Orchestra and Max Terr's Mixed Chorus. It was included on his Merry Christmas album of gramophone records released in 1945 on Decca Records. The collection consisted of ten songs on five 78 records, all of which had been previously released. Each one had a holiday theme with the exception of "Danny Boy." Prior to the long-playing album era, such assemblies were not common for popular music.
  
  The collection has remained in print through the vinyl and compact disc eras, currently as the disc White Christmas on MCA Records. The album itself has sold over 15 million copies, and is the best-selling Christmas album of all-time.
• Other artists who have covered the carol include Perry Como, Nat King Cole, Ella Fitzgerald, Mannheim Steamroller, Neil Diamond and Rascal Flatts.
• Doug Ingle's organ solo on Iron Butterfly's psychedelic rock epic "In-A-Gadda-Da-Vida" resembles variations on this carol.
• Bob Rivers parodied the song as "The Restroom Door Said Gentlemen" on his Twisted Christmas album. In that twisted tune, a guy finds himself in the ladies' room when a prankster switches signs on the bathroom door.
• Former Deep Purple guitarist Ritchie Blackmore and his wife Candice Night, who form Blackmore's Night, performed this with a Renaissance-style arrangement on the 2017 reissue of their 2006 album Winter Carols. Their version mentions that a savior is born, but doesn't name him as Jesus. While promoting the album, Blackmore noted that many traditional carols started out as pagan winter songs and didn't become religious until they were adopted and modified by the Catholic church.