The New Testament, as well as other early Christian writings, contains passages that promote monotheism and others that ascribe to Jesus divine attributes, and passages that stress the distinctness of the Father and the Son and others that fuse the two. These contradictory writings served as a fertile environment for the development of a number of conflicting and ambiguous doctrines. This confused theological language reflects more influence by the Roman understanding of divinity than by Jewish monotheism. Even if only the Gospel of John is considered and all other canonical and apocryphal Christian books are ignored, this single book would still provide too many discrepant, confusing, and vague statements to allow a harmonious, coherent, and clear picture of Jesus.
Soon after Jesus was gone, some Christian converts started to debate whether he was a mere human being, with some ascribing to the man divine attributes and others making him essentially a god. Whether Paul borrowed his views from someone else or developed them himself, which is far more likely, it was he who established the divinity of Jesus in Christianity. There were other views that genuinely reflected Jesus’ message and presented him as a man only, but Paul’s Jesus prevailed over the historical one.
The heated debates about the nature of Jesus that continued over decades and centuries resulted in the development of a number of different concepts and doctrines. All of these derived from the most fundamental doctrine of the Incarnation. Adoptionism, for instance, stated that the Son joined the Father in divinity at some point. Docetism claimed that Jesus had only an appearance and did not have a physical body. Theologians interested in Jesus’ divinity tackled issues such as whether the Son and the Holy Spirit were always present with the Father, the nature of the relationship between the three, and whether they were equal. Ultimately, the majority of Christians were led to accept the answers to these questions that the doctrine of the Trinity provided. But this doctrine itself was developed over centuries of controversies, and different theologians have understood and explained it differently.