Religious education may be the means whereby religion gains influence in political matters or over society at large. It usually involves segregation according to denomination, serves to reinforce existing prejudices, and may ultimately lead to discrimination, conflict and even war.
Denominational education exists world wide and is particularly important for Islam, Christianity and Judaism. It may be the main source of education and therefore be equated with prestige, making many converts for this reason and thus being a foundation for nationalism and other political policies. It may have an influence on the law. Religious teaching in schools is a matter of controversy in Western industrialized countries, especially where immigrant populations prefer religious teaching in their own traditions, rather than those of the host country.
In the case of Christianity, for example, most new catechisms and religious instruction books have no section on the basic beliefs of other religions. A vast majority of Christians do not gain insight in the spirituality and ethics of others.
For, teaching and professing the most fatal error of "Communism and Socialism," it is asserted that "domestic society or the family derives the whole principle of its existence from the civil law alone; and, consequently, that on civil law alone depend all rights of parents over their children, and especially that of providing for education." By which impious opinions and machinations these most deceitful men chiefly aim at this result, viz., that the salutary teaching and influence of the Catholic Church may be entirely banished from the instruction and education of youth, and that the tender and flexible minds of young men may be infected and depraved by every most pernicious error and vice. For all who have endeavored to throw into confusion things both sacred and secular, and to subvert the right order of society, and to abolish all rights, human and divine, have always (as we above hinted) devoted all their nefarious schemes, devices and efforts, to deceiving and depraving incautious youth and have placed all their hope in its corruption. For which reason they never cease by every wicked method to assail the clergy, both secular and regular, from whom (as the surest monuments of history conspicuously attest), so many great advantages have abundantly flowed to Christianity, civilization and literature, and to proclaim that "the clergy, as being hostile to the true and beneficial advance of science and civilization, should be removed from the whole charge and duty of instructing and educating youth." (Papal Encyclical, Condemning Current Errors: Quanta Cura, 8 December 1986).