Any comprehensive doctrine, religious or secular, can be introduced into any political argument at any time, but I argue that people who do this should also present what they believe are public reasons for their argument. So their opinion is no longer just that of one particular party, but an opinion that all members of a society might reasonably agree to, not necessarily that they would agree to. What's important is that people give the kinds of reasons that can be understood and appraised apart from their particular comprehensive doctrines.
John RawlsThe concept of justice I take to be defined, then, by the role of its principles in assigning rights and duties and in defining the appropriate division of social advantages. A conception of justice is an interpretation of this role.
John RawlsA political conception covers the right to vote, the political virtues, and the good of political life, but it doesn't intend to cover anything else.
John Rawls