This document provides an overview of Christianity and the Late Roman Empire from 69 BC to AD 400. It discusses the rise of Christianity under Jesus and his apostles. As the Roman Empire experienced political crises in the 3rd century, emperors like Constantine legalized and promoted Christianity. Constantine established Constantinople and convened the Council of Nicaea to address heresies like Arianism. After the fall of the Western Roman Empire, Christianity continued to spread throughout Europe led by figures such as St. Augustine, the Popes, and missionaries during the Post-Roman period.