"...to say we end the heartache, and the thousand natural shocks that flesh is heir to? 'Tis a consummation devoutly to be wished." - Hamlet, Act 3, ShakespeareIn Christianity, a goal for adherents is to receive eternal life, but what does that mean, exactly? There is some debate over whether or not those resurrected into eternal life will have a regular physical body like we do now, or if it will be some sort of glorified physical body which stays perfectly intact and is at a perfect age forever (like 35 years old), or if instead it will be a completely spiritual body with no physical matter at all. But one thing is certain: no matter what bodily form awaits you in eternal life, you will still be you. The only caveat is that, in most theoretical versions, you will no longer have the desire for sin.
That fact spawns the question: what are "you?"
What is your personality? Not personality type, but your actual personality. What is it that makes you act differently (even if marginally so) than anyone else in the world? What is it that drives your decisions and fosters your relationships? What makes you an individual? Christianity offers up the "soul" as the answer to these questions. This body you have now will die. Your soul, your "you," will allegedly continue on to face God on Judgement Day. By that time, your old physical body may have turned into clay.
In this perspective, your soul is presently using your physical body as a meat puppet through which it lives its life, and because of this, all of those nasty, evil, physical temptations nag at your soul to pleasure your body.
That is a great myth and all, but no soul exists. No soul exists, and I can prove it in two words: brain damage.
It is a well established fact that brain damage, depending on the type, will affect behavior. It can do so in very profound ways, ways which completely change a person's personality, ways that effectively change the outward manifestations which collectively we would consider to be evidence of a particular soul.
But, you Fool, that is BRAIN DAMAGE! (You might object.)
That is exactly my point. It is brain damage, not soul damage. If our bodies are nothing more than meat puppets to the soul, then there is no way in which your "you," your soul, can be changed directly by physical damage. At most, what would happen in this "meat puppet" case is that you would be unable to make the body do what you want it to do because the controls are broken. Your inward personality could not be broken, because, according to Christian theology, it is not at all physical. Yet reality is quite different.