I recently finished reading Justo L. Gozalez’ The Story of Christianity, both volumes. A friend loaned me the book after I remarked that I felt uninformed about the origins of things like the Apostle's Creed and the various Protestant denominations. Volume one works (basically) at the ascension until Luther's revolution; volume two completes the Reformation and brings the reader into the present.
The book is great. It's an engaging read, and while the author is Methodist, he gives an extremely balanced treatment to every form of Christianity, if slightly minimizing the Eastern Orthodox tradition. While the focus of the book is not theology, Gonzalez makes it easy to understand how world events influenced theology and vice versa. Patterns of cultural thought and world opinion make a big difference in how we view God!
One especially interesting aspect of the book for me was the origin of Methodism, since I was raised Methodist. It was really cool to find out that the Assemblies of God church actually grew out of the Methodist tradition, since I switched to an AG church during college. It was also intersting to note how the “traditions” of any one group or denomination often became very different from those of their founders!
The Story of Christianity was published in 1984, so its later chapters dealing with the ecumenical movement, Protestant theolgy, and Pope John Paul II are slightly dated, but most of what it misses will be fairly fresh in the mind of a modern reader, or at least more accessible in discussion with church leaders. As an introduction to the vast study of church history, I couldn't have asked for a better book, and I highly recommend it!