When you say, "according to christianity" things get a bit complicated. Christianity is viewed by many as catholicism & protestantism. However, those 2 organizations are the worst representatives Christianity ever had. They have mis-represented more than represented. Genesis 2:7 says, ".......the man came to be a living soul." Notice the verb 'to be', as opposed to 'to have'. Man does not have a soul, he IS a soul. It includes his head, his heart and everything else.