He puts the word “conscience” in quote-marks:

The subject then decides, on the basis of his experiences, what he considers tenable in matters of religion, and the subjective “conscience” becomes the sole arbiter of what is ethical. In this way, though, ethics and religion lose their power to create a community and become a completely personal matter. [My italics.]

This is no typo. Ratzinger has long disowned the notion of an individual conscience as we have long understood it in the West, as I explain at greater length in my forthcoming book. His view is that if your conscience goes against anything that the Pope says at any time, then it isn’t really your conscience. It’s a false conscience in a mirror of the Communist idea of “false consciousness”. Your real conscience, Benedict insists, is always in agreement with the Pope. ~Andrew Sullivan

Wow.  This is the kind of thing I would expect from thirteen year-olds who think willfulness and disobedience against their parents are the same thing as freedom.  That is, I would expect it from kids who are too young and immature to know and discern any better.  Where to begin….

Let’s start with what Pope Benedict said.  He referred to subjective “conscience,” so it makes sense that it would be put in scare quotes to make it clear that Benedict understands–properly–that real conscience is not subjective.  It is not some little personal voice in your head telling you what you personally find wrong, but serves as a witness to both the natural law inscribed in human nature and creation and the moral law revealed by God.  St. Maximos described this natural law in Ambigua 19 (translation by Louth):

Whence in both cases I think it necessarily follows that anyone who wishes may live an upright and blameless life with God, whether through scriptural understanding of the Spirit, or through the natural contemplation of reality in accordance with the Spirit.  So the two laws–both the natural law and the written law–are of equal honour and teach the same things; neither is greater or less than the other, which shows, as is right, that the lover of perfect wisdom may become the one who desires wisdom perfectly. 

Of more obviously direct application is Pope John Paul II’s 1998 encyclical Fides et Ratio, in which he described, among other things, the activity of conscience and its expression of natural and moral law.  For this reason, conscience is not an expression of subjective experience or subjective thought, but that faculty in man that recognises moral truth established by God:

This applies equally to the judgements of moral conscience, which Sacred Scripture considers capable of being objectively true.

Confusion about the nature of the truth, or a view that regards truth as subjective, will consequently distort the understanding of what conscience is and what it does: 

In the Encyclical Letter Veritatis Splendor, I wrote that many of the problems of the contemporary world stem from a crisis of truth. I noted that “once the idea of a universal truth about the good, knowable by human reason, is lost, inevitably the notion of conscience also changes. Conscience is no longer considered in its prime reality as an act of a person’s intelligence, the function of which is to apply the universal knowledge of the good in a specific situation and thus to express a judgment about the right conduct to be chosen here and now. Instead, there is a tendency to grant to the individual conscience the prerogative of independently determining the criteria of good and evil and then acting accordingly. Such an outlook is quite congenial to an individualist ethic, wherein each individual is faced with his own truth different from the truth of others”.

So a proper understanding of conscience would not tend towards an “individualist ethic,” and so would not have anything to do with subjective “conscience.”  We then properly use our faculty of conscience, as we do our reason, as a way of understanding and applying the truths that have been revealed to us:

Yet the Gospel and the Apostolic writings still set forth both general principles of Christian conduct and specific teachings and precepts. In order to apply these to the particular circumstances of individual and communal life, Christians must be able fully to engage their conscience and the power of their reason.

Thus Pope Benedict has drawn out the connections between individualism in reasoning generally and in moral reasoning more specifically.  Both privilege the self, both stress subjectivity, and both ignore the objective nature of intellectual and moral truth. 

The Catholic Catechism then states even more clearly what a good conscience involves:

A good and pure conscience is enlightened by true faith, for charity proceeds at the same time “from a pure heart and a good conscience and sincere faith.”

The more a correct conscience prevails, the more do persons and groups turn aside from blind choice and try to be guided by objective standards of moral conduct.  (CCC 1794)

Just as a proper use of reason is one illumined by faith, so it is with conscience.  Good conscience involves the submission to objective standards, and, of course, it is God Who has set down these standards and willed them for our improvement in the life of virtue leading to salvation in Christ. 

This is extremely close to an understanding that is the common inheritance of both Catholics and Orthodox, received from St. Maximos, who taught that subjective choice (gnome), deliberation and the choosing will (gnomikon thelima) itself were products of the Fall (and therefore did not exist in the Incarnate Word), whereas natural human will and human freedom in their proper forms always acted in accordance with the will of God.  Though I do not recall having seen references specifically to conscience in the works or studies of St. Maximos that I have read, it seems perfectly clear that obedience to divine will is what would show good moral judgement for St. Maximos.  Decisions cease to be a product of unnatural choice and more and more a product of free will, which naturally wills what God wills as it becomes purified of the effects of sin.  Free obedience is the true “freedom of morality,” and subjective choice and conscience are those things that keep us bound by the bonds of sin, autonomy and separation from God.

So when Sullivan prattles on about how “we” have long understood individual conscience in a certain way, by “we” he cannot actually mean Catholic and Orthodox Christians.  Indeed, I think he cannot be referring to most Christians over the centuries, but specifically in the tradition in which Pope Benedict is working Sullivan cannot be more horrendously wrong (as usual) when he suggests that it is somehow Pope Benedict who has departed from some proper consensus about the nature of conscience or when he implies that conscience truly should be understood as something subjective.  There would be almost nothing more abhorrent than this complete perversion of the meaning of what conscience is, which is right judgement in accordance truth and justice, which is to be in accord with God Himself.