A clandestine church (Dutch: schuilkerk), defined by historian Benjamin J. Kaplan as a "semi-clandestine church", is a house of worship used by religious minorities whose communal worship is tolerated by those of the majority faith on condition that it is discreet and not conducted in public spaces. Schuilkerken are commonly built inside houses or other buildings, and do not show a public façade to the street. They were an important advance in religious tolerance in the wake of the Reformation, an era when worship services conducted by minority faiths were often banned and sometimes penalized by exile or execution.