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.
This 1711 illustration for the Index Librorum Prohibitorum depicts the Holy Ghost supplying the book burning fire.
Orthodoxy is adherence to correct or accepted creeds, especially in religion.
Adherence to the Nicene Creed is a common test of orthodoxy in Christianity.