Scottish religion in the nineteenth century includes all forms of religious organisation and belief in Scotland in the 19th century. This period saw a reaction to the population growth and urbanisation of the Industrial Revolution that had undermined traditional parochial structures and religious loyalties. The established Church of Scotland reacted with a programme of church building from the 1820s. Beginning in 1834 the "Ten Years' Conflict" ended in a schism from the established Church of Scotland led by Dr Thomas Chalmers known as the Great Disruption of 1843. Roughly a third of the clergy, mainly from the North and Highlands, formed the separate Free Church of Scotland. The evangelical Free Church and other secessionist churches grew rapidly in the Highlands and Islands and urban centres. There were further schisms and divisions, particularly between those who attempted to maintain the principles of Calvinism and those that took a more personal and flexible view of salvation. However, there were also mergers that cumulated in the creation of a United Free Church in 1900 that incorporated most of the secessionist churches.
Catholic Emancipation in 1829 and the influx of large numbers of Irish immigrants led to an expansion of Catholicism, with the restoration of the Church hierarchy in 1878. Episcopalianism also revived in the nineteenth century with the Episcopal Church in Scotland being organised as an autonomous body in communion with the Church of England in 1804. Other voluntary denominations included Baptists, Congregationalists and Methodists, which had entered the country in the seventeenth and eighteenth centuries, expanded in the nineteenth century and played a major part in religious and educational life, while the established church lost its monopoly over schooling and poor relief. The attempt to deal with the social problems of the growing working classes led to the rapid expansion of temperance societies and other religious organisations such as the Orange Order and Freemasonry. There were also missions at home to the Highlands and Islands and expanding urban centres and abroad, particularly to Africa, following the example of David Livingstone, who became a national icon.