An altar is a place of sacrifice or an offering table as a place of worship for deities. Whether what Christians use in worship today may be an altar is a matter of dispute among the denominations. Since the liturgical reform of the Second Vatican Council, the altar has been the focus of many redesigns of Catholic church rooms. In doing so, one likes to orientate oneself on the early church. The Council refers to the "norm of the fathers". But how can this be reconciled with the widespread opinion that Christianity did not know any cult and no sacrifices in the beginning, but only love and sin feasts, celebrated in house churches? Only at a late stage, since the time of Emperor Constantine, did a real state cult with sacrifices, altars and magnificent sacred spaces develop, and the church still suffers from this historical ballast today. But is this really true? Or are these not rather clichés that need to be critically questioned? This volume cuts a few paths through the thicket and arrives at results that are as surprising as they are stimulating. "Heid is extremely meticulous in this work. The evidence he supplies is quite simply overwhelming. His command of the material is probably second to none. Altar and Church: Principles of Christian Liturgy is both necessary and magisterial."―Emery de Gaal, Mundelein Seminary "Heid's impressive knowledge of literary, iconographic and monumental sources, his exhaustive use of literature as well as his historical-critical method make the book an ' Opus aere perennius ' - to paraphrase Horace: 'a work more durable than brass."―Cardinal Walter Brandmüller, former President of the Pontifical Commission for Historical Sciences "This work will occupy an important place in the study of ancient liturgy. With impressive command of archaeological and textual sources, Heid challenges some of the commonly assumed narratives about the early Eucharist. No liturgical scholar can ignore this contribution."―Daniel Cardó, Benedict XVI Chair of Liturgical Studies, St. John Vianney Seminary, Denver "This book is a remarkable scholarly achievement. With an impressive command of both literary and archaeological sources, Stefan Heid challenges widely held assumptions about early Christianity and offers a fresh look at the foundations of Christian liturgy. Congratulations to CUA Press for making this important contribution available to Anglophone readers."―Fr. Uwe Michael Lang, Cong. Orat., St. Mary's University, Twickehnam, London Stefan Heid is Rector of the Pontifical Institute of Christian Archaeology, Rome.