Gregory was one of several notable scholars who in the 1970s were of vital influence into the evolution of the studying of the Late Antiquity period, drawing on complex early texts and analysing them in detail and publishing his findings.
[1] He has conducted detailed research into early Christianity, numismatics, epigraphy and wider socio-economic customs and many others during this period, covering Ancient Rome, Greece and Turkey.
[1] Gregory has also served as director of the Ohio State University Excavations at Isthmia and Co-Director of the Eastern Korinthia Archaeological Survey.
[2][3] One of his earliest books, Vox Populi, first published in 1979, explores religious tension and violence in the 5th century in Ancient Greece and the Middle East.
Other notable books include Panathenaia: Studies in Athenian life and thought in the classical age (1979), A social history of Philippi in the first century (1988), The soteriology of Clement of Rome within the intellectual matrix (1988), Archaeology and oligarchy at Isthmia (1989), The early Byzantine empresses and the Orthodox Church (1990), The sanctuary at Epidauros and cult-based networking in the Greek world of the fourth century B.C.