According to Christian understanding, when is a person truly dead? When does the soul leave the body? What is the situation of brain dead people who are kept alive only by machines?

Answer:

“Generally speaking, a person is dead when the heart has stopped beating. What is still subject of the medical, the philosophical and the ethical debates is the death of the brain as determinant for the death of a person. The Catholic Church has not officially spoken out against determining brain death in accordance with the appropriate methods of medical diagnostics because it is in favour of post mortal organ donation. Similar to German legislature it has not made a statement concerning brain death and its diagnosis. I believe this reticence to be appropriate because it is not up to the Church to define the diagnostics of death.” (Prof. Dr. Josef Schuster, Frankfurt)