On evolution: Richard Dawkins's "Blind Watchmaker." Also, read anything by Stephen J. Gould. His popular works are brilliant, though sometimes his biology and philosophy of biology are a little suspect. No less than Dawkins's... (I don't recommend either of Selfish Gene or Extended Phenotype unless you're familiar with evo-bio and can assess his arguments well).
On evolutionary developmental biology: Sean Carroll's "Endless Forms Most Beautiful"
On philosophy of biology: Kim Sterelny and Paul Griffith's "Sex and Death."
On cognitive science and philosophy of mind: Daniel Dennett and Douglas Hofstaeder's (Eds.) "Mind's I."
On epistemology and philosophy of science: Alan Musgrave's "Common Sense, Science, and Scepticism."
On Christian theology: Daniel Migliore's "Faith Seeking Understanding."
For Christian sermons: Frederick Buechner's "Secrets in the Dark."
More Christian stuff: Anything by Frederick Buechner (e.g., Beyond Words) and Adrian Plass.
On the historical Jesus: E. P. Sanders's "The Historical Figure of Jesus" (Sanders is an agnostic.)
On the Bible: James Kugel's "How to Read the Bible." Or Jacques Berlinerblau's "The Secular Bible." (The former is an Orthodox Jew, the latter is an atheist.)
For arguments for atheism: J. L. Mackie's "Miracle of Theism." (Stay far, far away from Dawkins here... Yes, Mackie's an atheist.)
I think these are on the top of my list of non-fiction works and authors. Not too much political history, I'm afraid. Lots of science and religion, from different perspectives, which is good, I think.