The historical significance of the victory of proto-orthodox Christianity can scarcely be overstated. The form of Christianity that emerged from the conflicts of the second and third centuries was destined to become the religion of the Roman Empire. From there it developed into the dominant religious, political, economic, social, and cultural institution of the West for centuries-down to the present. Christians living in the midst of these conflicts could not have imagined how important their outcome would be for the shape of western civilization. The repercussions are still felt today, in ways that even we may have difficulty understanding.
Throughout this study I have tried to hypothesize what it may have been like if some other side had "won." If the Marcionite Christians had gained ascendancy, would people still ask, "Do you believe in God?" Or would they ask, "Do you believe in the two Gods?" Would anyone except scholars of antiquity have heard of the Gospels of Matthew, Mark, and John? Would we have an "Old" Testament? How would the social and political relations of Jews and Christians over the centuries have been affected? Would Christians who rejected the Jewish God and all things Jewish feel a need to polemicize against and attack Jews? Or would they simply ignore Jews as not presenting any real competition to their own claims of the knowledge of the other God, who saved them from the creator? Would anti-Semitism be worse, or would it be nonexistent?
If, on the other hand, Ebionite Christians had gained ascendancy, would Christianity have remained a sect within Judaism? Would Christians today worship on Saturdays instead of Sundays? Would they keep kosher? Would these Jewish-Christians have wanted or been able to convert masses of people to their message of salvation, when conversion would have required men to undergo the operation of circumcision? Would Christianity have been anything but a footnote in the history of world religions?
We can probably say with some certainty that if some other side had won-Marcionite, Ebionite, some form of Gnostic-there would have been no doctrine of Christ as both fully divine and human. As a consequence, there would have been no doctrine of the Trinity. How would that have affected the intellectual life of the Middle Ages, the development of scholastic modes of argumentation, the modern Christian debates over the relationship between divine revelation (say, of religious mystery) and human reason (which cannot comprehend the depths of mystery)?
These questions affect everyone, not merely those who call themselves Christian. The beliefs, practices, and institutions of Christianity have played an enormous role in western civilization as a whole, not just for members of the Church. Take the New Testament itself, for example, considered by more people throughout the course of its history to be a single book, with a unified message that serves as the ultimate basis for this religion's faith and practice. The New Testament has been and continues to be the most widely read and revered book in the history of the West. It continues to inspire belief, to stimulate reflection, and to provide hope to millions. It is preached from the pulpit; it is studied in the university; it is attacked by skeptics; it is revered by believers. In the United States it is widely considered to have been a foundation document for the founders; it is quoted on the floor of the Senate to justify acts of war and at peace rallies to oppose the use of military force; its authority cited by both opponents and proponents of the right of a woman to have abortion, by both opponents and proponents of the death penalty, by both opponents and proponents of gay rights. It was used to justify slavery and abolish slavery. It has been used to justify capitalism and socialism. It has been used for good and for evil.
But where did this book come from? It came from the victory of the proto-orthodox. What if another group had won? What if the New Testament contained not Jesus' Sermon on the Mount but the Gnostic teachings Jesus delivered to his disciples after his resurrection? What if it contained not the letter Paul and Peter but the letters of Ptolemy and Barnabas? What if it contained not the Gospels of Matthew, Mark, Luke, and John but the Gospels of Thomas, Philip, Mary, and Nicodemus? Or what if it did not exist at all?