Rogue Classicism posts a call for academic papers on a fascinating topic. The summary speaks volumes about the difference Christians made in the ancient world, and the difference we can make today:
Scholars have reached consensuses that benefactions in the Graeco-Roman cities were not directed at the poorer segment of the society but at the citizen body at large and that the benefactors were not motivated by altruistic goals but by the desire of self-promotion. There has been a general tendency to emphasize the discontinuity between ancient euergetism and Christian charity. Recently … works have lent further support to this differentiation by bringing into focus such topics as the development of Christian rhetoric concerning poverty, invention of “the poor” and their acquisition of cosmic significance in late antiquity.
Good books on this subject: Rodney Stark’s The Rise of Christianity; David Batson’s The Treasure Chest of the Early Christians: Faith, Care and Community from the Apostolic Age to Constantine the Great; and Igino Giordani’s The Social Message of the Early Church Fathers.