Sectarianism is a political, cultural, or religious conflict between two groups. Prejudice, discrimination, exclusion, or hatred can arise in these conflicts, depending on the political status quo and if one group holds more power within the government. Often, not all members of these groups are engaged in the conflict. But as tensions rise, political solutions require the participation of more people from either side within the country or polity where the conflict is happening. Common examples of these divisions are denominations of a religion, ethnic identity, class, or region for citizens of a state and factions of a political movement.
While sectarianism is often labelled as 'religious' and/or 'political', the reality of a sectarian situation is usually much more complex. In its most basic form, sectarianism has been defined as, 'the existence, within a locality, of two or more divided and actively competing communal identities, resulting in a strong sense of dualism which unremittingly transcends commonality, and is both culturally and physically manifest.'
The term "sectarianism" is defined in the Oxford English Dictionary as "excessive attachment to a particular sect or party, especially in religion". The phrase "sectarian conflict" usually refers to violent conflict along religious or political lines, such as the conflicts between Nationalists and Unionists in Northern Ireland (religious and class-divisions may play major roles as well). It may also refer to general philosophical, political disparity between different schools of thought, such as that between Shia and Sunni Muslims. Non-sectarians espouse that free association and tolerance of different beliefs are the cornerstone to successful, peaceful human interaction. They adopt political and religious pluralism.
The ideological underpinnings of attitudes and behaviors labelled as sectarian are extraordinarily varied.