The concept of a dual human and divine nature in the person of Jesus is known as the Hypostatic Union, an essential component of modern Trinitarianism.
Yet it wasn’t until the Council of Chalcedon that we see the emergence of an official doctrine of the Trinity in a form that is recognisable with what Christian Trinitarians believe in today. This took place in the fifth century, over 400 years after Jesus!
The evangelical theologian and Professor Wayne A. Grudem sums this up as follows:
"A precise understanding of how full deity and full humanity" argues Grudem, "could be combined together in one person was formulated only gradually in the church and did not reach the final form until the Chalcedonian Definition in 451 AD
Source: [Grudem, Systematic Theology: Chapter 26 – The Person of Christ, 1994, p. 554.]