“This… is what it means to live in a secular age: we are inescapably aware that to believe in God is a choice. This puts a great deal more responsibility on the shoulder of the individual believer than in ages past. As a general matter, it is much more difficult to accept authority on the basis of its mere assertion. If religious authority is to have binding moral force over those under it, it must be experienced as convincing on a personal, subjective level.”