This paper gives an account of the establishment and expansion of a Faculty of Science at the Calvinist 'Free University' in the Netherlands in the 1930s. It describes the efforts of a group of orthodox Christians to come to terms with the natural sciences in the early twentieth century. The statutes of the university, which had been founded in 1880, prescribed that all research and teaching should be based on Calvinist, biblical principles. This ideal was formulated in opposition to the claim of nineteenth-century scientific naturalists that there was an inherent conflict between science and religion. However, despite their selection on the basis of their strict Calvinist beliefs, the first science professors attributed a certain independence to the domain of science. They agreed with the criticism of the conflict thesis, and tried to defuse the tensions between science and religion, although mainly at the level of philosophy and history, looking for example for harmony between science and religion in the past. Ironically, as a result of this approach, the Calvinist scientists mainly contributed to the acceptance of mainstream science in Dutch Calvinist circles, contrary to developments in other countries (notably the USA) where the conflict between science and orthodox Christianity has reasserted itself.