Rockne converted to Catholic after 7 years at ND. Both Rockne (Lutheran) and Parsegian (Presbyterian), 2 of the 3 greatest coaches in ND history (along with Frank Leahy) were great men and devout practitioners of their respective faiths. Hiring them didn't in any way hurt ND's faith mission.

Notre Dame emphasizes that each student should practice his faith whatever it is. Yes, ND has a Mass before very game but players understand and appreciate the university's religious tolerance.  So players such as Manti Te'o have felt very comfortable there.