This Christian philosophical investigation of his worldview according to the final edition of his Institutes (1559) is presented in commemoration of the birth of the Reformer of Geneva 500 years ago. The essay develops through the following stages. The introductory part firstly settles the debate on whether Calvin was primarily a Christian theologian or a philosopher. Calvin himself called his Institutes a "Christian philosophy" (philosophia Christiana) which, in contemporary terminology could be described as a (prescientific) Christian worldview. Secondly, the introduction indicates the method according to which Calvin's worldview will be analysed. It is done according to the only existing Christian philosophical historiographical method, viz. the problem-historical method, developed by the Dutch philosopher, prof. D.H.Th. Vollenhoven (2005a & 2005b) and afterwards further explained by his followers (cf. Bril, 2005 and Bril & Boonstra, 2000). The first main section indicates the failures of different efforts (mainly by theologians) to find a central idea governing Calvin's "system". Calvin research provides enough evidence today that there is no single "key" to unlock the door to Calvin's thinking. Not only one central dogma or principle, but many "keys" or biblical themes can be regarded as cornerstones of his so-called theology. This fact underlines the need for a broader Christian philosophical approach. The rest of the essay first investigates Calvin's view of reality (or his ontology) and briefly summarises his view on the human being. Next, the implications of his dichotomist anthropology and his distinction between an earthly and a heavenly kingdom for his view on societal life are explained. The following section discusses his epistemology and his view on the relationship between reason and faith, philosophy and theology. The results of this article can briefly be summarised as follows: The religious direction (or trend) of Calvin's worldview was his sincere desire to obey only God, his Word and his will. He therefore rejected the synthetic mentality of the early Church Fathers and Medieval thinkers who tried to achieve a compromise between the Bible and pre-Christian Greek and Roman philosophies. However, in his analysis of the structures of creation (his type of philosophy) Calvin did not succeed in fully realising his biblical normative approach. According to the problem-historical method, his type of worldview or "Christian philosophy" can be characterised in the following way: • Calvin was not a mythologising or cosmogono-cosmological thinker. To the degree that he was still thinking synthetically, he can be called a purely cosmological thinker. However, as a biblical thinker he did not exclude God from his thinking, and also disliked any speculation about God which pretends to know more about God than Scripture reveals. • Calvin rejected individualism as well as universalism and accepted a partially universalistic viewpoint, probably combined with a modified macro-microcosmos theory. (I indicate it as "modified", because the macro-microcosmos theory usually does not appear among purely cosmological partially universalistic thinkers like Calvin, but with cosmogono-cosmological thinkers adhering to a horizontal type of partial universalism.) • Calvin rejected monism (the idea that reality was an original unity) and adhered to a dualistic ontology. According to him reality consists of a transcendent part, viz. God and a non-transcendent part, viz. creation. Neither monism nor dualism is, however, in harmony with the Scriptures. Monism can only be true if we erase the distinction between God and creation. Dualism proposes two ultimate sources of reality, whereas the Bible teaches God as the one Origin of everything that exists.… [ABSTRACT FROM AUTHOR]