Justin Taylor posts his notes on what looks to be a very informative book on this topic by David Powlison. I highly recommend a careful reading of Taylor’s notes on Powlison’s book, which address the question posed in the title of this post.
Here’s a teaser in the hopes that you’ll read the whole thing:
Powlison argues that the Bible does not teach us to wage spiritual warfare using EMM [casting out demons]. Rather Scripture teaches us a different way to live the Christian life and fight our ancient foe.