from David Mathis, in the Introduction to Mathis and John Piper's With Calvin in the Theater of God:

Calvin so believed in the importance of the everyday activities of Christian life and mission that he had a strange but telling practice in Geneva. He was eager to see Jesus' church gathered on Sundays, but he was not happy for his flock to retreat from everyday life and hide within the walls of the church during the week. So to prod his congregants to be fully engaged in their city of Geneva — in their families, in their jobs, with their neighbors and coworkers — he locked the church doors during the week. It must have been hard not to get the point. He knew the place of God's people — gathered together to worship on Sunday, but during the week not hidden away behind thick walls of separation, but on mission together in God's world, laboring to bring the gospel to metro Geneva in their words and actions, in all their roles and relationships. (p. 23)