You can't compare Satan and the demons' belief to ours. They were created already saved but they rebelled and lost it. We are born lost and need salvation. It's completely opposite. The demons knew from their beginning exactly who Jesus is but Satan led them astray. Now they tremble because they know what they've thrown away and what's coming in the end.
Then you need to go back in time and tell James about that. He was clearly drawing a comparison between the benefit dead faith does for devils and the benefit dead faith does for living people.
