Heterodoxy
Heterodoxy, as opposed to Orthodoxy is the belief in something other (heteros) than the Orthodox Christian faith. In some senses, it is synonymous with heresy in that it is a departure from Orthodoxy, but it is distinct in that heresy by definition technically includes a specific choice to embrace and teach heterodox doctrine.
Heterodoxy may also be used to refer to all Christian confessions which are not the Orthodox Church.