Hello, your question and list include some different categories. It would be hard for anyone to include just five historically important doctrinal statements and works. I recommend Schaff's Creed's of Christendom or Leith's Creeds of the Churches for a collection of doctrinal statements from the early church through Protestant Orthodoxy.
As for catechisms, I'm partial to the Heidelberg for capturing Reformed thought. Luther's great and small are fine for Lutheranism, and the Roman Catholic one is quite substantive. There is even the old Baptist catechism, commonly called Keach's catechism that is helpful to consult.
However, to go behind creeds and catechisms means consulting some of the contributors to the creeds or major teachers of the church. There is also consideration for works that are "historically important," which may overlap with such contributors.
Here, I think the list cannot be limited to five, so I will just offer some suggestions:
Irenaeus, Against Heresies (Justin Martyr and Tertullian would be fine choices too, but I enjoy Irenaeus more in showing Christianity's response to Gnosticism). You can read this book for free at ccel.org.
Athanasius, On the Incarnation of the Word (the St. Vladimir's translation is the best available and it is quite affordable). This is a great little book that shows the major arguments in the Arian controversy. Of course, for a fuller expression there is also Athanasius's Against the Arians, but it is much longer.
Gregory of Nyssa, The Great Catechism, this is a fine little summary of doctrine by Gregory, one of the three Cappadocians (also available for free at ccel.org). I could recommend many other works by Gregory of Nyssa, Gregory of Nanzianzus and Basil of Caesaerea, and I highly recommend the Library of Christian Classics Christology of the Later Fathers for some good documents from Athanasius and the Cappadocians, including Gregory's catechism.
Augustine, On Christian Doctrine and The Enchiridion, while I wish all Christians also read his Confessions, On the Trinity (at least the first half of it, which is quite exegetical), and The City of God, these two little books are good summaries of his thought and quite readable.
John of Damascus, On the Orthodox Faith, this book was quite influential for both the eastern and western church (including the Reformers).
Thomas Aquinas, Sentence Commentary and Compendium. While I also recommend his lengthy Summa Theologiae and Summa Contra Gentiles, his compendium is his own summary of ST and there is a great English edition of it edited by Peter Kreeft called The Summa of the Summa. Thomas's Sentence Commentary is like a two for one because it will include Peter Lombard's Sentences, a collection of statements from the Church Fathers that was the dominant theological text in for about three centuries, and it has Thomas's commentary on Lombard. I also recommend Bauerschmidt's Holy Teaching, which is a great translation of portions of ST with some helpful notes for those who are being introduced to Thomas.
Martin Luther, Basic Theological Writings, I enjoy this English edition because it takes from many treatises to offer a broad picture of Luther's thought.
John Calvin, Institutes, while I don't recommend letting the Institutes be the only resource for Calvin's thought given his commentaries and sermons, it is still quite the work.
Richard Muller, Post-Reformation Reformed Dogmatics, I can't pick just one document from the era of Reformed Orthodoxy, so I will recommend this fine secondary source.
Thomas Grantham, Christianismus Primitivus, arguably the first Baptist systematic theology, it is somewhat a collection of his other works, but it will give you a taste of General Baptist theology from the seventeenth century.
John Gill, Body of Divinity, This encapsulates Particular Baptist theology from the eighteenth century, though I would also consult the more moderate views in works like Andrew Fuller's Gospel Worthy of All Acceptation. Both Gill and Grantham will draw from Scripture using Greek (and Hebrew for Gill), the Church Fathers (using Latin), and contemporary writers from other branches of Christianity in these works. I've found Baptist theology from this period to be quite substantive compared to some later versions.
Friedrich Schleiermacher, The Christian Faith, this one volume book is full of statements that are brief and penetrating. It will frustrate you, but most Christians from our age should read it.
Karl Barth, Dogmatics in Outline, while I could recommend much more from Barth, this little commentary on the Apostles' Creed will give you his basic theology.
Well this list is incomplete and full of omissions, but I've found the works above to be quite helpful.
BJ
