Most Christians know very little in the way of doctrine or theology or church history. For many these seem at best unnecessary, for others they are downright dangerous. I am familiar with such thoughts because I was born-again into the Christian faith among such Christians and such teaching. What really counted, what only counted, was my relationship with Jesus mediated through the Bible. Just me and God’s word supposedly illuminated by the Holy Spirit, and I was good to go. After several years I just could not be held in such a myopic box, and I was exposed to a Christianity that was rooted in history, and thus doctrine and theology took on a whole new meaning.
The term Christology means literally the study of Christ, just like any “ology” means the study of. Theology is the study of God, for example. If you want to know why Christology is so important, this piece by Timothy George at First Things is an excellent historical primer on the the role questions about the nature of Jesus played in early church history. Today we may take it for granted that there is a Trinity, and that Jesus is fully God and fully man, the second person of the Triune God, but in the early church this was no slam dunk. And these issues about the nature of Christ have profound implications for soteriology, or the nature of our salvation, but that is a topic for another blog post.
Every Christian should be familiar with Marcion and Arius because because it was their questions and assertions about the nature of Christ that the Church fathers had to wrestle with. In fact, heresy always forces the Church to grapple with fundamental issues about the nature and content of the Christian faith. We’re going through that today with questions about the nature of marriage. So I don’t think you could get a better, more concise overview of this critical period in Church history that led to a council in Nicea that gave us the creed by the same name we recite in church to this day.