My thought processes ARE my life. And certainly, as an atheist, I have faith in myself. There are systems of logic that are internally consistent.
Euclidean geometry is one example.
But, for the purposes of this discussion, the outside referrent is the rationality of the human mind, specifically MY mind. I accept MY capacity for rationality as an axiom, and the capacity of other humans for rationality I have determined by observation. It may be an act of faith for me to presume myself to be reasonable. One reasonably chooses based on one's own standards of reason. To choose otherwise, in the face of NO acceptable evidence, leads, as I said in my previous post, inexorably to gullibility.