The aim of my paper is to highlight that for Peirce the reality of God makes sense of the whole scientific enterprise. The belief in God is a natural product of abduction, of the "rational instinct" or educated guess of the scientist or the layman, and also the abduction of God may be understood as a "proof" of pragmatism. Moreover, I want to suggest that for Peirce scientific activity is a genuine religious enterprise, perhaps even the religious activity par excellence, and that to divorce religion from science is antithetical to both the scientific spirit and the real Peirce.
Understanding the real Peirce requires to deal with his religious concerns, which are increasingly recognized as being perhaps as philosophically important as his scientific concerns. Since a key notion in this project is the idea of "il lume naturale" that Peirce borrowed from Galileo, I want also to pay attention to that expression which during years I have been following through Peirce's papers and books.
In order to try to explain some of this, my paper is arranged into four brief sections after this already long introduction: 1) God and scientific inquiry; 2) The belief in God as a product of abduction; 3) Galileo and Peirce: Il lume naturale; and by way of conclusion 4) Some remarks on the religious framework of Peirce's approach.