Four parts (reprint, original is part 1 and 2). The first two volumes of Cambridge History of Christianity series: Origins to Constantine and Constantine to ca. 600. These books provide a comprehensive overview of the essential events, persons, places and issues involved in the emergence of the Christian religion in the Mediterranean world in the first six centuries.
Expensive on Amazon! Here only 30 euro (including postage, Netherlands only) and internationally 25 euro (excluding postage).