Final answer:
The dominant religion in Northern Ireland is Protestant Christianity, rooted in historical divisions between the predominantly Roman Catholic Irish heritage population and those of Scottish and English descent, with Protestant beliefs.
Step-by-step explanation:
The dominant religion in Northern Ireland is Protestant Christianity. This region of the United Kingdom has been marked by cultural strife often rooted in religious differences. Historically, the population with Irish heritage in Northern Ireland has been predominantly Roman Catholic, while those of Scottish and English descent have typically aligned with various denominations of Protestant Christianity.
These religious divisions have, at times, exacerbated tensions, resulting in violent conflicts such as those associated with The Troubles, a period of ethno-nationalist conflict in Northern Ireland during the late 20th century. The legacy of these divisions persists; cultural parades, like those celebrating King William of Orange, are part of this complex religious and political landscape. It is important to note that despite historical tensions, each generation strives for unity and peace, which could gradually ease historical animosities and strengthen centripetal forces within the society.