In Jesus, God really became one of us and thus our brother; nevertheless, he did not cease to be God at the same time and thus our Lord. The Council of Chalcedon in the year 451 taught that the divinity and the humanity in the one person Jesus Christ are united together “without division or confusion”. [464-467, 469]
The Church grappled for a long time with the problem of how to express the relation between the divinity and humanity in Jesus Christ. Divinity and humanity are not in competition with each other, which would make Jesus only partially God and only partially man. Nor is it true that the divine and human in Jesus are confused. God took on a human body in Jesus; this was no mere appearance (Docesitsm), but he really became man. Nor are there two different persons in Christ, one human and one divine (Nestorianism). Nor is it true, finally, that in Jesus Christ the human nature was completely absorbed into the divine nature (Monophysitism). Contrary to all these heresies, the Church has adhered to the belief that Jesus Christ is at the same time true God and true man in one Person. The famous formula, “without division or confusion” (Council of Chalcedon) does not attempt to explain something that is too sublime for human understanding, but rather draws the boundaries, so to speak, of the faith. It indicated the “line” along which the mystery of the person of Jesus Christ can be investigated.