Heresy in Christianity denotes the formal denial or doubt of a core doctrine of the Christian faith as defined by one or more of the Christian churches. In Western Christianity, heresy most commonly refers to those beliefs which were declared to be anathema by any of the ecumenical councils recognized by the Catholic Church. In the East, the term "heresy" is eclectic and can refer to anything at variance with Church tradition. Since the Great Schism and the Protestant Reformation, various Christian churches have also used the concept to include individuals and groups deemed to be heretical by those churches.