Christianity in the century both before and after Constantine’s conversion is familiar thanksto the written sources; now Ramsay MacMullen, in his fifth book on ancient Christianity,considers especially the unwritten evidence. He uses excavation reports about hundreds ofchurches of the fourth century to show what worshipers did in them and in the cemeterieswhere most of them were built. What emerges, in this richly illustrated work, is a religionthat ordinary Christians, by far the majority, practiced in a different and largely forgottensecond church. The picture fits with textual evidence that has been often misunderstood orlittle noticed.The first church-the familiar one governed by bishops-in part condemned, in parttolerated, and in part re-shaped the church of the many.Even together, however, the two constituted by the end of the period studied (AD 400)a total of the population far smaller than has ever been suggested. Better estimates are nowmade for the first time from quantifiable data, that is, from the physical space available forattendance in places of worship. Reassessment raises very large questions about the place ofreligion in the life of the times and in the social composition of both churches.