When an organization owns a piece of land which will never pass to another owner, it's known as a mortmain. A church's property is often protected by a mortmain. Mortmain literally means “dead hand.”
The noun mortmain is primarily a legal term, describing a kind of protection of a group's hold on property or land. Historically, buildings and land owned by a church organization would have a mortmain to protect the church against losing the property even after the death of the person in charge. In Old French, mortemain literally means "dead hand," from the Medieval Latin manus mortua, which in legal terms means "inalienable power."