The years 30 through 325 CE were the formative years of the Christian faith. During that time, a despondent gathering of Jewish followers of a crucified, Galilean preacher transformed themselves into a sect of spirit-led believers in the resurrection of Jesus. From the heart of the Jewish homeland they reached out with their apocalyptic message to dispersed Jews throughout the Roman Empire, and, through them, to non-Jewish sympathizers as well. Through the efforts of Paul and traveling missionaries like him, pagan belief in the salvation offered by the Jewish messiah grew until it soon outpaced the growth of Jewish members. By the second century, Gentile “Christians” were claiming sole possession of the Jewish scriptures and even identifying themselves as the true chosen people of the God of Israel.
Separation from its roots in Judaism resulted in periods of persecution for the young Christian religion across the empire. From ad hoc mob violence to official bans on the faith, Christianity persevered, lionizing the role played by the unfortunate martyrs who gave their lives rather than give obeisance to the pagan gods. Other Christians actively defended their faith through literary works known as “apologies.” They challenged the pagan philosophers at their own game explaining Christianity as another, better philosophy. As membership grew, so too did formalization of practice and organization. Liturgies developed that became standard throughout Christendom and procedures for joining the new religion were laid out. Creeds coalesced in short, memorable form what orthodox Christians should believe while the growing numbers of bishops ensured each catechumenate learned it thoroughly.
To combat the diverse variety of Christian beliefs, selections from the vast number of available Christian texts were made to shore up faith and provide a cohesive library expressing the “correct” view. By the end of the fourth century, a widely-accepted New Testament came to be established. In addition to the debates over texts, Christian theologians battled over such issues as the nature of Christ, his relationship to God, the nature of the Trinity, and the contents of the orthodox creed that would summarize these beliefs and hand them down to future generations.
Finally, after the last and greatest persecution of Christians in the ancient world, the Roman Emperor Constantine embraced Christianity as his personal religion and showed special favor to the 5% of the population that shared his views. From that time forward, Christianity would come to dominate the Western world.