Having started in the middle of them, I have just read the first of the five volumes of Jaroslav Pelikan's The Christian Tradition: A History of the Development of Christian Doctrine, namely The Emergence of the Catholic Tradition (100-600). For a week or two, I will be able to distinguish Marcionites from Donatists from Nestorians.
It is a work of astonishing erudition, "based on the study of the primary sources in the original languages--Greek, Syriac, and Latin", though he had "of course, consulted the sources in translation as well." The secondary sources he lists are in English, French, German, (modern) Greek, Russian, and Swedish. One, I noticed, was by the future pope Joseph Ratzinger, on "the noninstitutional aspects of Augustine's ecclesiology."
The erudition apart, Pelikan offers a readable account of his subject, the development of Christian doctrine, "what the church believes, teaches, and confesses." I imagine that he was correct in writing in the preface that "By using the index and by working his way through the narrative, even someone who knows no church history and no theology should be able to follow the plot and watch its movement." My own knowledge of church history and theology was not wholly lacking, but measured against this book it was and is exiguous.
At some point, I will need to go back and reread this volume. That will wait on many things, and perhaps on the fourth and fifth volumes.