In this classic reissue of the English translation of Morphologie des Luthertums, German theologian Werner Elert (1885-1954) looks at the writings of Martin Luther, investigating Luther's spatial concept of heaven; his definition of "the right hand of God" and "catholicity"; the reformer's thoughts on math, science, philosophy, and theology; and more.
The Impact of the Gospel, Dogma and the Church, and Philosophy of Life
I'm not going to give a specific rating because it's very hard to explain. I personally didn't love it because it wasn't quite what I was looking for. It's phenomenal in terms of explaining Lutheran doctrine as it develops within Lutheranism, so in that respect it's 5 stars. I wish he did more to actually defend those positions, but I suppose that's not what this book is meant to be.