Swann, S. Andrew -- Prophets (Apotheosis, book 1)

Religious galactic empires go to war over lost colony. Rogue AI shows up, declares intent to devour the universe. Everybody becomes very sad. I don't actually remember much of this book, except for a vague notion that a military stalemate that depends on both sides pretending not to know about an asset isn't very stable. Also, for a universe-devouring AI to quote the Book of Revelation doesn't really make it any scarier.

Books I have acquired recently
All the books I own