In Christianity, the Trinity includes three persons who are all fully divine: God the Father, God the Son, and the Holy Ghost.
Incarnation is the belief that God the Son “made himself nothing” by becoming a human being named Jesus.
This means that Jesus had two natures—human and divine. He was at the same time fully human and fully God.
In the Incarnation, the divine nature of Christ was joined—but not mixed—with human nature.
Text adapted from Simple English Wikipedia, Creative Commons Attribution-ShareAlike License 4.0.
