By the Second Century it had already been an established belief among the vast majority of Christians that Jesus was God. The view of what "The Son of God" meant evolved in Christianity's early days. It went from being a great honor, like the ancient kings received, to a semi-divine status like an angel, to divine status in the same category as God, to being equal with God in authority, to being God himself — "God the Son".
But in what sense was he God? That's where the debates and the branding of other theologians as heretics comes in. The Gospels, in some places, also make very clear that Jesus was a man, but in what sense was he human? How did his humanity and divinity coexist in one person? Was he half God and half man? Was he God who just appeared to be a man? Was he a man who was "promoted" to Godhood? I want to make clear that the Gospels and Epistles do not make any of this clear. And the answers that eventually led to the doctrine of The Trinity were by no means self-evident. Assumptions made by theologians were just as often based on what they thought was common sense or to avoid infelicitous outcomes. Here are a few of the possible "solutions" to the nature of Jesus that eventually were later deemed heresies:
- Modalism also called Sabellianism, teaches that the Father, Son and Holy Spirit are one and the same, and are different modes, manifestations, or expressions of a unitary God. When non-theologians attempt to explain the Trinity, this is often the explanation that they come up with. The actual doctrine states that Father, Son and Holy Spirit are not similar to a person taking on different roles in life, for example someone who is a manager at work, a parent at home and a softball coach on weekends. The doctrine of the Trinity states that Father, Son and Holy Spirit, while all are God, they are all separate "persons".
- Monarchism - There are various types of monarchism, they have in common the doctrine that the Son is subordinate to the Father in some fashion
- Adoptionism stated that Jesus did not pre-exist before his birth but was "adopted" as the Son of God at his Baptism (or Resurrection, or Ascension) due to his perfect, sinless life. His reward was resurrection and adoption into "the Godhead". This was put to rest around 200CE, but it seems to me that it has solid scriptural basis. You can see hints of this in both the Gospels and in Paul's writings. Like with everything connected to Jesus' nature, it's unclear.
- Docetism adherents believed that Jesus only appeared to have a physical human form. They believed that matter was inherently evil and therefore God couldn't have had a physical body. This belief didn't have much mainstream support, and can be found mostly among the various Gnostic documents.
- Apollinarianism stated that, although Jesus had a physical, human body, his "nature", or mind, was wholly divine.
- Monophysites believed that Jesus had only one nature — he started out wholly human, but his humanity was absorbed by his divine nature. They were the majority in the border regions of the Eastern Roman Empire and had competing bishops and patriarchs when the Crusaders conquered Jerusalem and the surrounding area.
- Monothelitism was a theological response to Monophysitism, holding that Jesus had two natures, human and divine, but one "will", which was divine.
- Arianism has been latched onto by modern day non-Trinitarians to support their belief that the early Christians were not Trinitarians. Arius didn't teach that Jesus was not God, but that Jesus, God the Son, was created first by God the Father and that the rest of the universe was then created by the Son. The main difference between Arianism and the version of Trinitarianism that the majority of theologians were adhering to was that the Trinitarians believed that the Son and the Father were "co-eternal", i.e. there was never a time when the Son did not exist, while the Arians taught that the Father pre-existed the Son. This dispute was what spurred the Council of Nicaea. Arians for hundreds of years constituted the majority of Christians outside of Rome and Byzantium. It effectively died out when Charlemagne accepted Catholic Christianity.
- Nestorianism was a branch of early Christianity wherein their founder Nestorius taught that Mary gave birth only to Jesus' human nature. They argued about the term "Mother of God", preferring the title "Mother of Christ". Nestorius' followers fled persecution relocating to the Persian Empire where they further developed the idea that Jesus, although one person, had both a human and a divine nature. Nestorians flourished under the Persians and Nestorian churches continued to exist even after the Muslim conquest of Persia.






