"Come in and have a look."

The welcoming sign on the gates of a ramshackle building with metal walls off a highway near the industrial city of Tianjin in northern China masks a grim reality: This is an underground Catholic church barely tolerated by Communist Party authorities.

Inside, a 30-year-old priest tells hundreds of Catholics, some sitting cross-legged on the floor because the pews are full, that he had just visited a parishioner, diagnosed with cancer years ago and told he was soon going to die.