Senior bishops fear that the Church of England's historic link with the state is under threat following moves to end the prime minister's involvement in key clerical appointments.
They have told The Sunday Telegraph that removing Downing Street's role in the appointment process could lead to disestablishment.
Leading Anglican figures have expressed concern at the long-term significance of a decision taken by the General Synod to give the Church the final say in choosing bishops, a process previously open to the scrutiny of the prime minister.
Gordon Brown has moved to reassure the Church of England that it will not lose its established status as the country's official church, headed by the Queen as supreme governor and "defender of the faith".
But one bishop warned that the change was "pulling at the thread" of a relationship that has stood since the reformation. Another said: "I don't think people have properly considered how this might play out in the future. We should have been given a chance to discuss the issue before being presented with it as a fait accompli."