I spent some time with an old acquaintance there, a self-designated atheist. Interestingly, he went to the bother of "becoming ordained" so that he could perform weddings (which he has), yet he has abandoned, seemingly, the institution in his personal life.
Like so many such atheists, he sees a major issue to be one of authority. Where does a mainline Christian pastor get his or her authority? Where does the Pope? He asked these questions, clearly brandishing his "ordination" as carrying as much authority as either of these (being a relativist as well as atheist). Of course, we Catholics can guide any such questioner to the sixteenth chapter of St. Matthew when Our Lord proclaimed Simon to be kephas / Πέτρος ("Rocky") and "on this rock," said He, "I will build my Church" (18-19). Catholicism is historical; Benedict XVI stands as our 265th pontiff since St. Peter.
Now, my atheist friend has several presuppositions that keep him from acknowledging such biblical authority, most of which were laid to rest as unsubstantial in epistemology by the great British Catholic thinker - some say the greatest mind to come through Eton and Oxford - Monsignor Ronald Knox (and others). But he still gives credence to "higher criticism" of liberal schools of thought, like, for example, the so-called "Jesus Seminar." Let us just say that authority for them comes from whomever thinks and sees things their way; i.e., the scriptures they see as "authentic" prove that Jesus, as it turns out, was a Jesus Seminarian!
Let me say, in the hope that my old friend will possibly read this post: authority is posited from a much higher and substantive source than one's individual opinions and life experience. We are created, finite, and mortal. We will answer to the One from whom we have our lives on-loan, ontologically speaking. And the Catholic Church has and provides the greatest and most coherent explanation of our lives, our purpose here on earth, and, please God, our ultimate telos.