H. J. Spijker (1801-1870) was one of the most important liberal administrators of the Nederlandse Hervormde Kerk (Netherlands Reformed Church) of the second half of the nineteenth century. He was first heard of in a discussion about a revision of the 'Algemeen Reglement van de Nederlandse Hervormde Kerk' (The constitution of the church). In this discussion he proved to be an ardent supporter of a more democratic church structure. In 1852, Spijker became a member of the 'Algemene Synodale Commissie', the Synod's executive committee. Being in favour of the separation of Church and State he played an important role in 1853 by urging for moderation when relations between Protestants and Catholics were severely tried, owing to the restoration of the Catholic hierarchy (1853). This did not make him beloved by all. As a result he lost his position in the organisation; he returned in 1860 in the national church council, however, first as chairman of the Synod and a year later as chairman of the 'Algemene Synodale Commissie'. His most important contribution again had to do with a more democratic church structure. In 1852 this liberal attitude brought him into contact with J.R. Thorbecke, who found a position for him in the 'Departement van Eredienst'. When he died in 1870 the separation of Church and State, as laid down in the constitution of 1848, was almost completely realised. Spijker's contribution had been considerable.