Books & Culture is published by the folks at Christianity Today. Now Christianity Today (CT), you may be aware, is the flagship publication for the intelligent conservative side of Christian thought, just as The Christian Century is for the liberal. CT has some rather surprising stances in some areas. They see combating poverty worldwide as a vital task for Christians, and they support wise stewardship of the environment. On issues such as homosexuality and abortion their stances are more predictable.
Books & Culture, on the other hand, takes a balanced and even nearly academic approach. It is not by any means a bastion of liberalism, but the essays are intelligent, balanced, and well thought out. The magazine publishes both individual reviews of books and thoughtful essays that touch on multiple recently published titles on a given topic.
It's a great magazine if you're interested in the serious treatment of topics such as religion, literature, culture, history, and related areas.