Blaise Pascal (1623-1662) was a French physicist, mathematician and religious philosopher, who made important advancements in the field of hydrodynamics (Pascal's principle) and created Pascal's Wager, a Christian apologetics argument. The SI unit of pressure and a programming language are named after him. Mathematicians may recognize him for Pascal's triangle, a useful introduction to probability distributions.
He was also working on a book called Pensées , however he died before he could finish the book. It was supposed to be an argument for Christianity. It was never refuted according to apologists, but that's probably because he never even finished the book before apologists decided to piece together some notes he made.