Sullivan is broadly right about conservatism. For the preservation of liberty, the skeptical, dry, philosophically modest conservatism that Sullivan argues for is a much better bet than any system based on a belief that human beings, or their societies, can be transformed by state power.
That's what the book is about. Derb then argues that the rest of the book is about being gay and Catholic. Just for the record (and this may be because Derb only skimmed much of the book): there is almost no discussion of the subject in the book. There is a serious attempt to describe a Christianity that is not fundamentalist, but that non-fundamentalist faith applies to everyone, gay, straight, male, female, young, old, and of every race and culture. Yes: it's an argument for a Christianity based in love, sacrament, mystery, compassion and humility; it is an argument against excessive doctrinal obsession, minute moral regulation, and constant guilt. I have a feeling that many heterosexual Christians will understand what I'm getting at.
The book, due out October 2, can be pre-ordered here.