Agreed it would make for a lopsided war. But I think once they had control of enough Muslim countries they probably wouldn't attack the west all at once. They would continue with terrorism trying to bring down western economies while denying culpability. And they would attempt to raise the price of oil.
However with real war, they would proceed with the plan they have been executing for years only more intensely. They would attempt to conquer the marginal countries physically close to them. Northern Africa, Eastern Europe, Indonesia. They would count on the West to stay aloof from these battles.