Militant Catholicism refers to radical Catholic believers who believed that the only way for Ireland to remain a Catholic country was to combine together in lay organisations, to work in politics and society for the overthrow of the Protestant culture and to replace it with a strictly Catholic ethos.
In the newly independent Ireland, Militant Catholicism played a crucial role in asserting the Catholic Church's influence on both politics and society. It was pivotal in helping to shape and consolidate public opinion, in copper-fastening the Catholic-Irish identity and in helping to enshrine the moral code in Irish law. It also had a resounding impact on the drafting of the 1937 Constitution of Ireland. Moreover, its influence can be seen in the growth of democracy and the political party system in Ireland, in the ideologies embraced by Fine Gael, Fianna Fail and Clann na Poblachta, and consequently on governments' social and economic policies.