I have come across a fantastic blog/website called "Da' Purple Soapbox" which is full of all sorts of gems, however one thing I came across was a link to a free e-book written by Dr. Jeffrey Khoo, that explores the roots of many heresies from ancient and modern times, along with their main proponents, and those who were recognised as solid defense against these heresies. Well worth a read and passing onto others too. The link to the book is in the article itself, but I strongly suggest having a wander around this guys blog, and maybe even getting in touch, he's a smashing chap.