The history of Christianity is essential to understanding the formation of Christian doctrine. So, historical theology provides research of the way that the Church has undergone for interpreting the Scripture under various conditions determined by the different epochs. One of the subdivisions of theology, Christology, studied the logical formulations that can unite all Christians as to the nature of Christ, the central figure of the religion. Although this question seems answered now, early Christian scholars divided into the adherents of Apostolic Christianity, Ebionism, Gnosticism, and Docetism because of the issue.
Historical theology describes the disagreement regarding Jesus Christ in terms of canonical Christianity, which is Apostolic. Namely, the early Christians in their majority believed in the texts written by the successors of the Apostles (hence the name), who declared that Christ was divine and human. Moreover, he was the Savior sent by God, his Father (Duesing & Finn, 2021). There emerged other beliefs, although they were later refuted, condemned, and considered heretic by the Church. As such, Docetism followers viewed Jesus as a divine being that only appeared to be human (Duesing & Finn, 2021). Next, Ebionists declared that Jesus was indeed a Messiah, but for Jews, and that he was a virtuous yet not divine man (Duesing & Finn, 2021). Finally, Gnosticism considered Jesus a production of God, sending secret knowledge to save humanity (Duesing & Finn, 2021). Thus, it is apparent that the nature of Christ was not obvious to the early Christians.
Thus, it could be concluded that to comprehend the meaning of the Christian faith, indeed, it is necessary to learn its history. Historical theology serves as a study for this subject and makes this knowledge accessible to the public. As such, the essence of Jesus Christ is understood uniformly among Christians nowadays, although it was not always the same. The history contains several alternative beliefs as well as the theological reasons for why they vanished.
Reference
Duesing, J. G., & Finn, N. A. (2021). Historical theology for the Church. B&H Academic.