In 1645 the City of Haarlem ordered that a new Calvinist church be built to replace the mediaeval Sint Annakapel (Saint Anne's Chapel), which had become too small to hold services in. The council opted for a design by Jacob van Campen, which preserved Lieven de Key's tower of 1613. The building, which was called the Nieuwe Kerk (New Church) from the beginning, has hitherto only been the subject of stylistic scrutiny in art-historical writings. Van Campen's design was thought to have been prompted by the desire to have the new building harmonize with the existing tower. The present investigation however shows an iconographical approach to be indispensable for a better understanding. The architectural form of the Nieuwe Kerk appears to refer to an image current in that period: the Temple of Jerusalem, as depicted in Reformed bibles. There are striking correspondences between the church building and the reconstruction of the Temple of Jerusalem by the French Hebrew scholar, François Vatable. The building is moreover equipped with incurving buttresses which derive from the reconstruction of the Tempele of Jerusalem by the Spanish Jesuit, Villalpando. These structural correspondences could indicate several symbolical relationships which were thought to exist between this church building and the Tempel of Jerusalem. Van Campen introduced incurving buttresses to the architecture of the Republic in the churches of Renswoude and Hooge Zwaluwe, which were built almost concurrently (1639-1641). Several Calvinist places of worship and synagogues were later given such buttresses. It is quite likely that this was intended to express a symbolical relationship with the Tempel of Jerusalem. The ceiling paintings in the New Church refer to a legend which tells how the citizens of Haarlem played an important part in one of the Crusades. The Haarlem magistrates probably commissioned these paintings in order to press home the Calvinist view of the authorities as guardians of the true faith. Study of the Nieuwe Kerk has clearly shown that its design and furnishings express the religious notions of the Reformed church. This is diametrically opposed to the traditional art-historical view that seventeenth-century Dutch Protestant churches were modelled on Italian examples in which not a trace of Protestantism is to be seen.