Forgiveness and Death

I saw a Jew once argue against the divinity of Jesus because 'God can't die'. My thought was that an equally amazing notion is that God could change. My understanding is that the Jewish concept of God is timeless and unchanging. The Jewish God is also a God of Justice. (harsh justice by today's standards, but 'punishment for transgressions', at least)
Christianity brings to this a forgiving God, a God that suspends harsh justice out of love. A God that CHANGES his mind. But this is incompatible with the old testament version of God. How can an unchanging God change?

A classic paradox:
Q: If God is all powerful, can he create a wall so strong that even he can't break it down?
A: Yes he can, and he did. Then he broke it down, but it killed him.
God, in order to forgive, had to alter a fundamental part of who he was, in so doing he became something else, he died. The real action of salvation wasn't at Calvary, it was in heaven, probably 'before' our space/time was created. This may have fractured him into the trinity.

What really irks me is that I of all people come up with this stuff, while after 2000 years of development Christians are using CHICK TRACTS?!? What is that about?