The divine and human natures in Christ are personally united. So there are not two Christs, one the Son of God and the other the Son of Man. But one and the same person is the Son of God and Son of Man (Luke 1:35; Romans 9:5).
The divine and human natures are not mingled into one substance, nor is one changed into the other. Each keeps its own essential properties, which can never become the properties of the other nature.
The properties of the divine nature are these: to be almighty, eternal, infinite, and to be everywhere present, to know everything, and so on. These never become properties of the human nature.
The properties of the human nature are to be a bodily creature, to be flesh and blood, to be finite and physically limited, to suffer, to die, to ascend and descend, to move from one place to another, to suffer hunger, thirst, cold, and the like. These never become properties of the divine nature.
The two natures are united in one person. This union is not the kind of joining together and connection that prevents either nature from having anything in common with the other personally. It is not like when two boards are glued together, where neither gives anything to the other or takes anything from the other. But here is described the highest communion that God truly has with the man. (paragraphs 5-9)
Condensed from CONCORDIA: THE LUTHERAN CONFESSIONS, copyright 2005,2006 by Concordia Publishing House. Used by permission. All rights reserved. To purchase a copy of CONCORDIA, call 800-325-3040.