Apart from Apostle Paul and Jesus Christ, St. Augustine is another prominent figure hen explaining the history of Christianity. St. Augustine was both a bishop and a philosopher, he shaped the Catholic Church doctrines and established the litmus assessment for orthodox through and up to the reformation of the Protestants and beyond (Baptist). His achievements were majorly influenced and built around both the Latin and Greek philosophical traditions. The traditions provided the ideological frameworks and dialectical tools which Augustine later used in explaining Christian theology. As he explains, nothing is wrong with paganism, but simply not a whole account of actuality.
Arius believed that Jesus was not equal to God by nature and that He was God’s first creation (Turner). Arius believed that there was no trinity as God is unique and exists alone, not dependent on anything, and immutable, whereas Jesus, the Son, cannot be immutable to God and is not self-existent; all which meant Godhead was unique and could not be shared. The ideas had a huge impact on the early Churches as defined orthodoxy with many creeds. Arianism still exists with many giving biblical arguments that tend to support their argument that Jesus is not God.
The knowledge of historical Jesus emanates from the attempts of scholars to reconstruct the teachings and life and Jesus as detailed in the Bible through historical analytical techniques (Academic rigour). The sources to establish and study the historical Jesus majorly include Jewish and Roman sources like Josephus and Tacitus, respectively. The issues with these sources are that they are independent of each other, through which their similarities and differences are employed in authentication processes. Gospels should, however, be read not as history remembered but as prophesy historicized, based on the belief that they were by those who witnessed them in that time, not who try to create it.