Cosmas Shi Enxiang died in custody at the age of 94 after being accused of running unregistered churches.
In China only government-approved churches are free to meet in the open. It means millions choose to meet in secret.
Bishop Shi from Yixian in northeast China led an underground Catholic Church but was arrested in 2001and his family say he's been held ever since in a secret location.
They claim they've been told by authorities that he's died but have been given no details about the cause of death.
His treatment is part of a wider crackdown on Christianity which has seen whole congregations put in prison while churches have been torn down.
Anti-persecution charity Christian Solidarity Worldwide is calling on China to rethink how it views the religion.
Speaking on Premier's Voice for the Voiceless, spokesperson Stuart Windsor said: "What are the Chinese frightened of?
"It's the Gospel, it's the power of the Gospel of Jesus Christ to change lives. The apostle Paul said 'I am not ashamed of the Gospel'.
"The Church is so huge in China. We're talking about 100 million members underground and above ground. The Chinese have tried to stamp the Gospel out... we need to pay tribute to these men of God who need to be added to that list in Hebrews 11."
Listen to Mervyn Thomas and Stuart Windsor speaking to Premier's Dave Rose: