This morning we spent some time at the local market offering people gospel leaflets and trying to get into conversation with them, invite them to church and share a little about how fantastic Jesus is. Towards the end of our time there a Jehovah's Witness stopped me and began asking a few interesting questions - most of the normal things they like to talk about. Right at the the end she asked me this, "If Jesus is God, how can God have died? If Jesus didn't entriely die how can that be a full and complete payment for sin?" She didn't give me a chance to answer, however if she did here's roughly how I would have responded.
1 - A question - When the body dies, does the soul die? My answer and her answer ought to be the same; no the soul does not die. What then is death? Death, as we know it, is the end of the life in the body. It is when the body has no more life in it.
Now I cannot claim to understand how Jesus can be God and man at the same time, only that the Scripture clearly declares it to be true. However with the eternal Son of God taking on the nature of man, God came among us in human form. Therefore when Jesus died, when life left his body, it is perfectly correct to say to those who killed him, "You killed the Author of Life," which is precisely what the disciples do say (the "Author of Life" being a title that is applicable to God alone.) It is therefore no lie and misunderstanding to say that God died. Life left his body and he was dead.
2 - A misunderstanding - In some ways the most important part in Jesus death was the three hours in the darkness as he hung on the cross. During that time he experienced what Revelation calls the second death. Beyond what we can grasp, he experienced the eternity of hell on behalf of everyone he will save in those three hours. He paid the the total price of our sin so that we could be set free from the total price of our sin. Physical death (the first death if you like) is in comparrison only a symptom of sin that points to the reality of the second death (pictured in Revelation as a lake of fire). The death Jesus died was far more than simply his life leaving his body.
3 - A problem - The real problem comes if Jesus is not God. If he is merely a super angel then he is an innocent third party to sin (neither the sinner, nor the sinned against), and the cross is therefore, as a certain Mr Steve Chalk has scandalously said, "cosmic child abuse." It would be unjust in the extreme and could not be performed by a God who is love.
But because Jesus is God, we see on the cross God (the one sinned against) dealing with the penalty of sin within himself on our behalf. In Jesus the injured party consumes the injury so that the sinner may be healed and forgiven and restored to his side.
Acceptance of the doctrine of the trinity is the only way of grasping the full import and enormity of what happened when Jesus died. "For God so loved the world that he gave his one and only Son, that whoever believes in him shall not persih, but have eternal life." He paid for the most expesive free gift that could ever be bought with his own precious blood.