Brad Long makes a well researched case that the evil we are experiencing from ISIS today is far greater than just acts of extreme violence and political revolution, which can be defeated by military might alone.
Behind it and other forms of Islamic Jihadist activity is a deeply entrenched spiritual power and personality of evil. I highly recommend this book as a well researched and footnoted exposure of the underlying historical and spiritual issues which must be understood to withstand this major movement.
It is a balanced treatment, able to make a distinction between different philosophies among the Islamic faith. His second book will describe some of the spiritual resources needed to partner with further military engagement.