"The Death of Adam" - Marilynne Robinson

This collection of essays by the author of "Housekeeping" and the current "Gilead", contains defenses of Calvinism, several investigations into the reasons for the coarsening of society and support for evironmentalism as well as a history of the McGuffey Readers. They are densely written and sharply argued and even where I disagree with her she makes me believe there's some underlying validity to her points.
She is politically liberal (in the sense of defending the weak and comforting the poor and infirm) and unabashedly Christian (and not some weak willed apologetic one). Her faith and Calvinist theology are the explicit subject of most of the book and the rationale for the rest.
If you're not religious I still suggest checking out the book. Her historical analysis of Calvinism and Puritanism is fascinating. By actually reading the works of those two strains of theology she does much to dispel the picture of them as dark, brooding things lingering over New England. Instead they were liberating as well as responsible for instilling a deep sense of personal accountability into their adherents' actions. The very fact that they were the wellsprings of town meeting based government and abolitionism makes me think she's more right than much of the history I've learned.
So pick it up. It's just returned to print and is readily available.