What was Lay Investiture during the Protestant Reformation?

Lay Investiture was a significant conflict during the Protestant Reformation concerning the appointment of church officials, where secular leaders, rather than the church, appointed bishops and other clergy. This practice was seen as undermining the spiritual authority of the church and led to tensions between religious and political powers. Reformers, including Martin Luther, argued for the separation of church and state, advocating that spiritual leadership should be determined by the church alone. The controversy highlighted broader issues of authority and governance within Christianity during this tumultuous period.