This is actually the second or third time I've read this little book. It's a good one to keep on your shelf to reference or re-read from time to time. MacArthur wrote the book in the early 90's at the time when the health wealth and prosperity gospel message was abounding in the church. This book deals with the spiritual warfare movement that was also taking place coincidentally at the time. He takes aim at false doctrine and errant strategies for taking on Satan. In some ways its a rebuke to false teachers. But, more importantly to me, is it's usefulness in refreshing the follower of Christ in key truths of spiritual warfare. Ephesians 6 features prominently as one would expect. Despite how often I have read on the spiritual armor that Paul writes about in Eph 6, I always learn something new.
The "ah hah" which occurred during my re-read of this topic was that of the 6 pieces of spiritual armor believers are to equip ourselves with, 3 pieces should always be on and 3 pieces should always be at the ready. That was a "click" for me which now allows me to mentally organize the spiritual "equipment" in a new and more effective way.
The shield of faith, as an example of a piece of armor at the ready, is now more easily understood as quite simply - faith in God - and something large enough to hide behind during battle. One may say - yes its obvious the "shield of faith" equates to trusting God. But, I think the problem is that we often misconstrue faith in God to mean faith in outcomes. I think, however, the faith really needs to be placed in who God is and His promises, not what we want. Likewise, the belt of truth - always to be worn - is a reminder to eliminate encumbrances to spiritual growth. In other words, get rid of stuff that will distract us and trip us up.
There is much more to learn by reading the book and even though it's been in print for many years - the insight is timeless!