 The Vatican has excommunicated a former ambassador to the U.S. Walter Ratliff has details. Archbishop Carlo Maria Vigano is formally outside the church and cannot celebrate or receive its sacraments. It was an inevitable end for the firebrand conservative who became one of Pope Francis' most ardent critics. Schism is one of the gravest crimes in canon law. It occurs when someone withdraws submission to the Pope or from the communion of Catholics who are subject to him.