http://www.amazon.com/Resurgence-More-Conquerors-Michael-Hari-ebook/dp/B00XGS5ZGWThis is by the same author as
Brethren Thinking. It begins with a history of the marketing of Christianity, which is by far the most interesting part. I would say that the core message is that Christianity wasn't spread by talk, it was spread by showing others what Christianity means through actions. In other words, Christians lived a better, more moral life and had better schools and, at some times, better technology. So others were drawn to Christianity because of this. The application to us is obvious. We need to do more and talk less, starting with making the Mennonite connection work.