In my classes, we are discussing these issues right now. Some of my students get a little freaked out about it. James' command [echoed by Peter in 1 Pe 5.7-9] to "resist the devil" in Js 4.7 is not a theoretical, spiritual antidote for tough times. James wants believers to actually do it.
So, how does that work? What does it look like to "resist the devil"?
I'm showing them this lecture/talk that I think helps to biblically answer the how-to question when dealing with demonic activity. Some of the stories are intense and downright crazy, but Driscoll's thoroughly biblical approach is what must be noted.