The 3rd Mark of the True Church

"Anabaptists insisted that mutual accountability was a third mark of the true church alongside the two recognized by the reformers (faithful preaching of the gospel and proper administration of the sacraments). It was the absence of mutual accountability, they argued, that prevented the reformers' churches from being communities of disciples; sound doctrine was not enough on its own."

Stuart Murray, The Naked Anabaptist, 103.