Know the Enemy

It is an adage in the military that you need to know your enemy in order to fight him.  It really is the same in Christian apologetics; if you don’t know what the heretics are teaching, then it is difficult to teach against them and win people to the truth. I just finished reading Irenaeus’ Against Heresies, and he had this to say in his preface of Book IV:

The man, however, who would undertake their [heretics] conversion, must possess an accurate knowledge of their systems or schemes of doctrine.  For it is impossible for any one to heal the sick, if he has no knowledge of the disease of the patients.