Why God and Geometry? This particular combination can be surprising for the unacquainted with the history of philosophy, yet everyone who has learnt anything of Plato knows that "God geometrises continually." Then, if the entire history of philosophy boils down to a handful of footnotes to Plato, as Alfred North Whitehead believed, one or some of them must refer to the relationship between geometry and God. As both philosophy and geometry have long been among the areas of my interest, I simply could not have failed to investigate what it means that "God practices mathematics." There are a plethora of works on the history of geometry, both comprehensive and focused on individual periods. There are also plenty of course books in the history of philosophy, and no fewer course books and monographic works on the history of the Christian dogma. The author is keen to see what you can find out studying works of both the types, something that has never been tackled straightforwardly in any of them. Making no claim on completeness, the book succeeds in paving the way and grasping a handful of ideas that are hidden from the view while the reader examines one side of this conjunction.