A liberal in his early years, he was converted about 1830 to strict Calvinist orthodoxy, becoming one of the pillars of the Réveil, a religious revival and antimodernist movement. In politics Groen provided the theoretical basis for the Dutch denominational political party system. He prepared the way for the foundation of the Anti-Revolutionary Party formed in 1878 by Abraham Kuyper (Kuyper, Abraham), who, unlike the aristocrat Groen, was capable of rallying the orthodox Protestant lower-middle classes. Although Groen was a member of the Second Chamber (1849–57 and 1862–65), his significance rests on his published works. His handbook of Dutch history (1846) gives his views on the providential genesis of the Protestant Dutch republic and kingdom. In Ongeloof en Revolutie (1847; “Unbelief and Revolution”), he identified disbelief in religion with the spirit of the French Revolution.