He can think, and he can make free choices. However, all his operations are in the natural order. Being without divine and Catholic faith he cannot enter the realm of the supernatural. Unfortunately, he is unaware of his plight. Mr. C is a person who not only has the natural powers of intellect and free will functioning in the natural order, he also has faith.
Faith is our supernatural intellect, so to say.
It is a power similar to the intellect, and yet it is entirely above the natural order. It is in the supernatural order. Briefly, Mr. A before Mr. B generally is entirely unaware that he is lacking something. Likewise, Mr. Be before Mr. C generally is unaware that he is lacking something. The difference between Mr. A and Mr. B is not just a matter of degree , it is a matter of kind .