Reddit reviews Lectures On Groups And Vector Spaces For Physicists (World Scientific Lecture Notes in Physics Vol. 31)

Agnostic here. I'm afraid it is not so easy to rule out the presence of brilliance and religion in a scientist or mathematician. Here is a list of living scientists who are christians (it is only a part of a much larger list going back several centuries).

Here are some examples with whose work I am more or less directly familiar.

John Polkinghorne was a student of Paul Dirac, and he has written a couple of books that are very lucid introductions to Quantum Mechanics.

Christopher Isham has written books on

• Quantum Theory,
  
• Modern Differential Geometry for Physicists and
  
• Lectures On Groups And Vector Spaces For Physicists.
  
  I have only actually read the first one on Quantum Theory.
  
  Edward Nelson is a mathematical physicist who has also contributed to quantum theory.
  
  Don Knuth is a mathematician and computer scientist who created the computer typesetting system, TEX, as well as a number of important theoretical developments, (e.g. the Robinson–Schensted–Knuth correspondence, and the Knuth–Bendix completion algorithm)
  
  Maddening, ain't it? But that's just how it is.