Christian democracy is a political ideology that seeks to apply Christian principles to public policy. It emerged in nineteenth-century Europe. It was a direct descendant of conservatism. Conservative parties initially were mainly confessional. They shifted, largely under the influence of Catholic social teaching (e.g. Rerum Novarum), towards social conservatism. It continues to be influential in Europe and Latin America, though in a number of countries its Christian ethos has been diluted by secularisation.

In practice, Christian democracy is often considered conservative on cultural, social and moral issues (social conservatism) and progressive on fiscal and economic issues. In Europe, where their opponents have traditionally been secularist socialists, Christian democratic parties are moderately conservative overall, whereas in the very different cultural and political environment of Latin America they tend to lean to the left.

Examples of Christian democratic parties include the German Christian Democratic Union (CDU), the Christian Democrat Party of Chile, the Christian Democratic People's Party of Switzerland, the Partido Popular in Spain and Fine Gael in Ireland.