Every Christmas, millions gather in cathedrals and concert halls for a spectacular tradition: the sing-along "Messiah." It's a celebration of one of music's finest miracles, where a composer drafted the world's perennially favorite oratorio in just 24 days. Choruses and solos range from stirring to dizzyingly complex - and together the songs express the full significance of what Christ came to this scarred world to achieve on our behalf.David B. Smith...