This book "The Spiritual Man is Mad" was written under the mighty anointing and inspiration of Holy-Spirit of God; to reveal certain deep areas of prayer warfare, that would be an additional weapon or instrument in demonstrating faith.
Here, insight reveals that a bit of madness is needed to our faith to do the unusual things that happen in the physical sense.
The spiritual minded person needs to exhibit irrational behavior, which produces good results. Remember, "Until you take a step of stub born faith, your opposition will not retreat". For instance, it is a stupid step for a person to empty his account and give it out as donation to somebody else ministry or life.
Faith substantiates your desires!