Christianizing the Roman Empire (A.D. 100-400)

Ramsay MacMullen's Christianizing the Roman Empire, A.D. 100 to 400, published by Yale University Press in 1984, is a scholarly history examining how and why the Roman world actually converted to Christianity, arguing against accounts that credit theological persuasion alone by giving serious weight to coercion, miracle claims and the material advantages of imperial favor after Constantine. MacMullen was a leading historian of the later Roman Empire known for reading sources skeptically against their own rhetorical self presentation. Its strength is that willingness to ask an unglamorous, structural question, why did conversion actually happen at scale, rather than restating Christianity's own account of its triumph. Its limit is that MacMullen's emphasis on coercion and material incentive as major drivers is itself a debated interpretive position among historians of late antiquity, not a settled consensus, so a claim treating his account as the single explanation for Christianization rather than one serious contribution to an ongoing debate overstates its standing.