“IT WASN’T JUST A CHRISTMAS SONG — IT WAS A LIGHT THAT NEVER WENT OUT.” Six legends stood together — Dionne Warwick, Barbra Streisand, Barry Gibb, Dolly Parton, Diana Ross, and Céline Dion — their voices rising like a single breath of hope. The song began as a carol, but became something eternal: a bridge between heaven and home. And when the last note faded, it didn’t end — it lingered, like love itself.

Released in 1968, “Words” stands as one of the most enduring love songs in the...