This PhD thesis describes the implementation of a new church in Geneva at the end of the 19th century within the framework of the Kulturkampf (1870-1907). Connected with the Dutch, German and Swiss old-catholic movement, the catholic-christian church arised from the schism with the Roman Catholicism after Vatican I. Its implementation is however strictly dependent on the political and religious situation of the canton of Geneva. This Church indeed was above all liberal and national, it was supported by the political authorities, mainly of radical obedience. The study of the actors of this reform, their ideas and their concrete realizations shows how individuals who considered themself "modern" did to reform the Catholicism in a context where they had the open field and a state subsidy.