In Christianity, the term non-denominational refers to those churches that have not formally aligned themselves with an established denomination, or remain otherwise officially autonomous. This, however, does not preclude an identifiable standard among such congregations. Non-denominational congregations may establish a functional denomination by means of mutual recognition of or accountability to other congregations and leaders with commonly held doctrine, policy and worship without formalizing external direction or oversight in such matters. Some non-denominational churches explicitly reject the idea of a formalized denominational structure as a matter of principle, holding that each congregation must be autonomy.