Final answer:
The early development of Christianity is best described by C. Persecution by the Roman authorities, as Christians faced tension and persecution for their refusal to participate in state cults. Under Roman Emperor Theodosius, Christianity eventually became the state religion, leading to greater unity and organization.
Step-by-step explanation:
The early development of Christianity was marked by several key characteristics, but the statement that best describes it is persecution by the Roman authorities. Early Christians experienced significant conflicts with the Roman Empire due to their refusal to participate in state cults, which was viewed as treasonous. This conflict led to periods of intense persecution under emperors such as Nero and Diocletian. Furthermore, a lack of centralization and institutionalization characterized early Christianity, with a wide variety of practices and theological disputes among different sects. It was not until the adoption of Christianity as the state religion by Theodosius in the late 4th century that the church began to see a more unified structure.
Prior to this, Christianity spread across the Roman Empire through missionary work, forming congregations that gradually became more organized after the conversion of Emperor Constantine. His conversion encouraged members of the Roman elite to convert to Christianity, changing it from a religion of the common people to one that carried social and political advantages. The establishment of official doctrines and texts, such as the Nicene Creed from the Council of Nicea in 325, emerged as means to unify Christian beliefs. Despite its initial diversification and fragmentation, Christianity's proselytizing nature and the efforts of its leaders were instrumental in its spread.