1. Bush believes that God wanted him to be President.
2. Invading Iraq was the most important decision that Bush took.
3. God couldn't have wanted Bush elected in order to do something disastrous.
4. De-escalating in Iraq would be basically admitting a disastrous failure, even if it would somewhat limit the consequences of failure compared to staying indefinitely.
5. Keeping the same force level doesn't appear to be working, has no political support, and could lead to de-escalation.
6. God must have made it possible for his chosen President, George Bush, to obtain victory in the most important action Bush took.
7. Neither de-escalation nor keeping the same force level leads to victory.
8. Therefore, God must want Bush to take the only course that leaves a chance for victory, even if it is no more clear to us how that will occur than it was clear to Abraham's wife, Sarah, that at 90 years old she would have her firstborn child, Isaac.
It's not hard to figure out what role is being played by those who oppose the escalation.
I'd also note that someone with more religious sophistication than Bush could question #3 above, but I doubt Bush will.