..which is Sullivan's tendency to characterize aspects of Church teaching he doesn't agree with as strange blips on the radar screen of Christian tradition, as somehow worthy of a separate category.
It's very bizarre. Look, everyone knows (or should know) that understanding Church teaching is a knotty business. However you want to put it - development, change, deeper understanding of revelation, or varied expressions of teaching in varied cultural contexts - the point is you could, if you drew on everything even remotely authoritative that has been produced by not only the official Church, but theologicans and moralists who are regarded as most authoritative (Augustine, Aquinas, etc), you could play proof-text all day long with a lot of issues. As an historian, I am all for being honest about that, I have for years played with the idea of doing a book on several especially contentious issues on which the Church seems to have developed its thinking, with an eye towards helping people make sense of that in the context of Christ's promise and the apostles' understanding of the presence of the Spirit, which is Truth, in the Church.
However, given this, there are certain themes and elements of Christian teaching that are really, taken as a whole, consistent over time. Let's take this end-of-life stuff. Certainly, the issue has changed dramatically in the last hundred years, and Christian ethicists have constantly had to rethink things as new technologies emerge.
But the one thing that has NOT changed, that we can hold onto even in the midst of questions about whether something is treatment or care, ordinary or extraordinary, prolonging life or prolonging the death process is this: Quality of life judgements are not, and never have been an acceptable element in traditional Christian thinking on this, and I don't mean "quality of life" as we factor it into the question of weighing burdens and benefits: I mean: because this person has this disability or this condition, he or she is better off dead.
There is, believe it or not, a difference.
That is the fundamental, core issue here. Christians stand in reverence of life because it is a gift of God. All of our thinking must revolve around that point: God is the author of life, so we do not have the right to intentionally take it away, and...God is the author of life, so that when we discern, through all the clouds of unknowing, that it is time, we gracefully allow him to take that life and embrace it as his own in eternity.
It is not an easy determination, and we all have faced it and we all will. But....what Andrew Sullivan and others who choose to appeal to Catholic teaching on the issue is that amid all the other discussions and points, we cannot ever let ourselves start talking about human beings as if they are better off dead. Many of us hear hints of this in discussions about Terri Schiavo, and it makes us uncomfortable and concerned.
Letting God, through nature, take created life back to him is one thing. Declaring that one who bears this gift under difficult circumstances would be better off dead is another.