Religious nationalism is the relationship of nationalism to a particular religious belief, dogma, or affiliation. This relationship can be broken down into two aspects: the politicization of religion and the influence of religion on politics.
In the former aspect, a shared religion can be seen to contribute to a sense of national unity, a common bond among the citizens of the nation. Another political aspect of religion is the support of a national identity, similar to a shared ethnicity, language, or culture. The influence of religion on politics is more ideological, where current interpretations of religious ideas inspire political activism and action; for example, laws are passed to foster stricter religious adherence.
Ideologically-driven religious nationalism may not necessarily be targeted against other religions , but can be articulated in response to modernity and, in particular, secular nationalism. Indeed, religious nationalism may articulate itself as the binary of secular nationalism. Nation-states whose boundaries and borders are relatively recent or that have experienced colonialism may be more prone to religious nationalism, which may stand as a more authentic or “traditional” rendering of identity. Thus, there was a global rise of religious nationalism in the wake of the end of the cold war, but also as postcolonial politics (facing considerable developmental challenges, but also dealing with the reality of colonially-defined, and therefore somewhat artificial, borders) became challenged. In such a scenario, appealing to a national sense of Islamic identity, as in the cases of Pakistan and Indonesia, may serve to override regional tensions.
The danger is that when the state derives political legitimacy from adherence to religious doctrines, this may leave an opening to overtly religious elements, institutions, and leaders, making the appeals to religion more ‘authentic’ by bringing more explicitly theological interpretations to political life. Thus, appeals to religion as a marker of ethnicity creates an opening for more strident and ideological interpretations of religious nationalism.
Many ethnic and cultural nationalisms include religious aspects, but as a marker of group identity, rather than the intrinsic motivation for nationalist claims.
Christian nationalists focus more on internal politics, such as passing laws that reflect their view of Christianity. In the United States, Christian nationalism tends to be conservative. Distinctive radicalized forms of religious nationalism or clerical nationalism (clero-nationalism or clerico-nationalism) were emerging on the far-right of the political spectrum in various European countries specially during the interwar period in the first half of 20th century.