One hundred pages. Three chapters. Twenty-five theses. The whole of Christian theology briefly described, yet full and complete. A Short Systematic Theology is amazing in its brevity, touching on all major theological issues in Christianity. Author Paul Zahl took as his inspiration Summa totius Christianismi (A Summary of the Entire Christian Faith) by Theodore Beza, a one page description of all of Christian theology.
While some would argue that the exposition of Christian theology requires a longer book (or set of books), Zahl does a brilliant job of condensing Christian theology into a very readable book. His twenty-five theses are as follows: theology is Christology; Jesus was the first Christian; the connection between the historical Jesus and the Jesus of today is His resurrection; there is no present form which can adequately describe and locate the presence of Christ in the present; the risen Christ is present in His absence; the presence of Christ's absence is found in works of love; Christ can be present in human love insofar as it resembles His love; the risen Christ is expanding the frontiers of space and time as compassionate love is practiced; Christ is the beginning and end of theology; Satan is the second subject of theology; the Holy Spirit is God's unseen presence; the governing content of Christian theology is atonement; Christ died for our sins; Christ died for our sins; the "for-ness" of God in regard to humanity is prior in theology to the "with-ness" of God; Christ died for our sins; Christ died for our sins; the trinity is the final development in the logic of systematic theology; the atonement conveys the God who is moved both by the suffering and the sin of the world; theology is a testing of the spirits in accordance with the gospel of forgiveness of sins; theology grounded in self-criticism and in the confidence of forgiveness produces freedom; theology is inductive, not received; in true theology, church and tradition always play secondary roles to the gospel of atonement; the critical method, in theology and life, can exorcize the world of false gods and assumptions; the world exists between Christ's death and our death--the Spirit acts in the present through freedom in love.
If you understand these theses, says Zahl, you will understand Christianity and Christian theology.