Let me take a try at answering the ops original question...

First you have to start with some presuppositions: that god exists, that he is intelligent, all knowing, and has all power and authority of all of creation.

He spoke creation into existance, he said "let there be light" and there was light...therefore we can see a very important principle that is essential to all of existance...the natural world is bound by the authority of God's word. It can not exist without it. The indformation recieved from Gods word is necessary for existance.

And I mean this in a very real and physical sense...information is an integral and essential part to nature...consider quantum physics for example where merely the act of observing particles, or recieving information, has an effect on them. The point being, that information can and does have real physical effects on the natural world.

So heres the problem, what happens if God violates his own word, would this undo creation itself since existance hinges on the authority and truth of God's word?

In the beginning, in the garden of eden, when Adam and eve sinned, God had warned them the result of sin was death. God can not violate his own word, or it would null that words authority (This was part of the plan of satan, to make god into a liar and hypocrite so that he could ascend in power over him...all of which is impossible of course).

So since God can not violate his own law, that sin = death, the only alternative for him was to put a sacrifice in place to recieve the punishment...and he so loved the world, that he gave his own son to be that sacrifice...he could have let the world perish in its sin, but jesus took the punishment for us instead.

If he had not, God would have been bound by his original law to exact punishment on us because he can not violate his own word, otherwise satan would rule.

Now that might seem like just a legal argument, and you might ask, why not just not let anyone be punished? The problem as I said is that Gods word is a binding law on nature...he cant just say sin is death one day and contradict himself the next because the chaos of the hypocracy of gods word would undo creation...as I said, creation only exists by gods word, let there be light etc., man does not live by bread alone but by every word that proceeds from the mouth of god. Therefore god can not lie, existance depends on it.