I never thought the day would come that I would find myself quoting Alice Cooper on spiritual matters, but he recently said that he believes in the existence of demons because "Jesus spent half his time dealing with demons and throwing them out of people." Ha Ha. Man, that's refreshingly simple (He sounds like one of those followers of "the" Nazarene).
"Much of our discernment of Satanic powers comes as we follow the Holy Spirit's guidance in mission and ministry. As we begin initiatives for the kingdom, events will turn in a direction precisely calculated to block our efforts. These events will often be enveloped in a cloud of lies, accusations and misunderstandings which is the devil's native atmosphere. If all this comes with an especially disabling power behind it. Satan is probably involved."