It just wasn't the brutal battle between good people and evil people in the streets of Las Vegas that people might have been expecting. The characters spend the majority of the books not understanding the supernatural events around them, sometimes being angry about it and lashing out at God for it. Flagg spends the book sure of himself and his invincibility, he sees and knows everything. So God's side doesn't send an army, or even warriors. It's just a few simple people with a lot of issues, and they were there just to stand up with faith. That was the whole point, I think, to prove their faith in the worst moment and show Flagg that he didn't actually have control. He didn't see everything, and didn't know what was going on after all. So a few people who were uncertain (a rock star, an retired atheist professor, a farmer) and didn't look like the best the world had to offer turned to God and defied evil knowing it would kill them. It was a devastating defeat for evil, because it rubbed the failure in Flagg's face. It used Flagg's own devices against him. Flagg wanted the battle, but God never did. I like the idea, evil prepares an army, gathers weapons and nukes, uses magic to watch its enemies, and plans a massacre, and good reacts by sending an old man with arthritis to insult it, and still wins.