HONG KONG — The Christian hymn “Sing Hallelujah to the Lord” has emerged as the unlikely anthem of Hong Kong’s protests against an extradition bill that have drawn millions of people onto the streets.

A hymn sung by Christian groups participating in the anti-extradition Hong Kong protests has caught on and become an unlikely anthem for the movement of millions in the streets. For the past week, ...

On a footbridge leading to the Hong Kong’s Legislative Council building, about three dozen people are intoning “Sing Hallelujah to the Lord,” giving barely a pause after the short, four-line verse ...