It wouldn't be the holiday season without a rousing singalong to Mariah Carey's Christmas classic, "All I Want for Christmas Is You." Thankfully, James Corden has gifted us a holiday episode of "Carpool Karaoke" beyond our wildest dreams.

James invited Mariah herself to help out with his Christmas shopping. Naturally, when they turned on the radio, only one song could possibly be playing, and it was.

But this episode of "Carpool Karaoke" had a twist. Not only was Mariah along for the ride, but all the guests on the show this year had secretly been filmed singing "All I Want for Christmas Is You" with James. Adele, Lady Gaga, Selena Gomez, and even Chris Martin join in the fun thanks to a little time-traveling TV magic.

Truly, this is a holiday gift for the ages. God bless us, every one.