History of Secularism concerns the development of ideas and institutions concerning the separation, differentiation or changing relationship between religious authority and nonreligious spheres such as government, education, law and public administration. The term secular derives ultimately from the Latin saeculum, referring to an age or worldly temporal realm, and acquired several meanings over time.
Secularism can refer to constitutional separation between religion and government, state neutrality among religions, restriction of religious institutions from exercising political authority, or philosophical commitments to organising public life without reliance on religious doctrine. These meanings vary by country and historical period. Secularism is therefore not synonymous with atheism. A secular state may protect religious belief and practice while maintaining institutional neutrality, and secular individuals may themselves hold religious beliefs.
In medieval Europe, the distinction between secular and religious life existed within Christian society rather than through a modern separation of religion and state. The Latin Church possessed extensive legal, educational and political institutions, while secular rulers governed kingdoms and empires. The term secular could distinguish clergy associated with ordinary worldly parishes from members of religious orders living under monastic rules.
Conflicts between papal and royal authority, such as the Investiture Controversy, demonstrated that political and religious jurisdictions could be distinguished even when society was overwhelmingly Christian. Medieval universities also developed intellectual institutions that eventually contributed to the differentiation of theology, law, philosophy and natural inquiry. Secularism therefore has historical roots in institutional differentiation as well as in later arguments for explicit separation of religion and government.
The Reformation altered European relations between religious and political authority. Protestant reformers challenged papal jurisdiction and established churches connected to territorial states, while Catholic rulers defended or reformed existing institutions. The resulting religious conflicts encouraged political theorists to consider how governments could maintain civil order amid religious disagreement. The Peace of Augsburg and later settlements permitted limited confessional coexistence but generally linked political territory with religious authority rather than creating modern secular states. Over subsequent centuries, religious pluralism and repeated warfare weakened assumptions that political unity required religious uniformity. The growth of commercial society, scientific inquiry and professional administration also produced institutions increasingly capable of functioning independently of ecclesiastical authority.
Enlightenment political thought was crucial to the development of modern secularism. Thinkers including John Locke, Voltaire, Montesquieu and Jean Jacques Rousseau debated conscience, civil authority and religious institutions. Their positions differed considerably, but many argued that political legitimacy should not depend entirely on theological claims. The American constitutional tradition established restrictions on religious establishment at the federal level while protecting religious exercise. The French Revolution pursued a more confrontational restructuring of church state relations, confiscating church property and reducing ecclesiastical privileges. These examples demonstrate that secularism can emerge through different constitutional models, ranging from accommodation and neutrality to more radical attempts to reduce institutional religious influence.
The nineteenth century saw secularism develop into organised social and political movements. In Britain, George Jacob Holyoake popularised the term secularism in the 1850s and promoted an ethical approach based on human experience rather than supernatural authority. Secularist organisations campaigned for secular education, civil marriage, freedom of conscience and reduced ecclesiastical influence. Similar movements developed elsewhere in Europe and the Americas. At the same time, nationalist governments sometimes adopted secular institutions as part of state modernisation. The relationship between secularism and nationalism varied considerably, because some secular states protected religious diversity while others attempted to suppress public religious influence.
Secularisation is related to secularism but is not identical to it. Secularisation generally refers to social or institutional processes through which religious authority, participation or influence declines or becomes differentiated from other social institutions. Secularism is more often an ideology, political principle or institutional arrangement concerning the place of religion in public life. A society can become more secular through urbanisation, education, industrialisation and social change without adopting an explicit secularist ideology.
Conversely, a state can adopt secular constitutional principles while its population remains highly religious. The distinction became particularly important in sociology, where theorists debated whether modernisation necessarily produces declining religious belief. Evidence from different societies shows that secularisation has followed multiple trajectories rather than one universal pattern.
Twentieth century secularism developed in different forms across the world. Turkey under Mustafa Kemal Ataturk adopted a strongly secular republican framework that subordinated religious institutions to state authority. The Soviet Union promoted state atheism rather than neutral secularism and therefore represents a different model. India adopted a constitutional system that sought equal treatment of multiple religions rather than a strict French style exclusion of religion from public life. In the United States, establishment and free exercise principles developed alongside a highly religious society. European states also developed varied arrangements, including established churches in some countries and stronger institutional separation in others. These differences demonstrate that secularism is not a single political formula.
Contemporary secularism continues to shape debates about education, religious symbols, public ceremonies, family law, religious exemptions and the limits of state neutrality. Human rights law generally protects freedom of religion and belief while also protecting freedom from religious coercion. Modern secular constitutionalism therefore attempts to manage competing claims rather than simply eliminate religion from public life.
Critics of secularism sometimes argue that apparently neutral institutions can reflect historically Christian or culturally specific assumptions, while defenders emphasise equal citizenship and protection of conscience. The historical significance of secularism lies in its role in redefining the relationship between religion, political authority and public institutions. Its development is best understood as a series of different responses to religious diversity, political power, intellectual change and changing conceptions of individual rights.
