Generally neglected by scholars of the history of oriental studies, Johann Heinrich Hottinger's Historia Orientalis (1651, 2nd ed. 1660) is one of the most significant contributions to the history of Islam to have been published in the seventeenth century. This article analyses Hottinger's interest in Islam and in Arabic sources across the range of his writings and his correspondence, with a special focus on the Historia Orientalis. It discusses the philological and antiquarian standards by which he assessed Arab history and it describes the numerous Islamic manuscripts he exploited. It also examines the manifold ways in which Hottinger used the Koran and other Islamic sources to corroborate his apologetic Protestant interpretation of Church history. It thus sheds a light on the impact that a combination of confessional commitment, antiquarianism, and philology had on the rise of oriental studies in seventeenth-century Europe.