在宗教學的研究領域中，有一個令人困擾的難題，那就是對於學術核心的定義：何謂「宗教」？至今尚未有一個普獲接受的共識。然而，在政府機關中，宗教行政部門，基於種種原因，卻被迫面對「定義宗教」這項業務，畢竟，唯有先定義「宗教」，才有可能界定「宗教行政」的範圍，以免宗教行政包山包海，或與其它行政領域重疊，導致權責不清。然而，這份行政工作並不容易，畢竟，政府機關基於「政教分立」的原則，辦理這項業務必須考量宗教平等、宗教自由、依法行政、比例原則、公益原則、輿論期待、宗教團體需求……等諸多限制。故本文將從政府認定宗教之必要性、合法性、各國立法例，以及我國現況，分別予以討論，並針對我國未來行政機關如何建立一個合法合憲、符合國情，並且正當合理的制度，提出建議。

Within the academic field of religious studies, the definition of religion has been a troublesome question at the core of the academic research— What is religion?— however, even today there has yet to be an accepted consensus on the issue. Nevertheless, Taiwan’s Administrative Department of Religious Affairs is forced to confront the definition of “religion” to avoid overlap with other administrative areas. To define a religion is an undoubtedly difficult business. The government must take into account religious equality, freedom of religion, separation of church and state, the principle of proportionality, public good, and public expectations. This paper discusses how the government defines a new religion in Taiwan and other countries and tries to provide reasonable and suitable suggestions.