The Apostasy That Wasn't: The Extraordinary Story of the Unbreakable Early Church:

The Apostasy That Wasn't: The Extraordinary Story of the Unbreakable Early Church by: Rod Bennett
Non-fiction: Religion, E- book

This book deals with the real history of the time that many people say the "Great Apostasy" happened.  Just yesterday I was talking with someone that believes all the anti-Catholic lies including that Constantine "made" the Catholic Church and caused his religion to be the official and only religion of the Roman Empire destroying all the "real" Christians who some how were also perfectly erased from history until X preacher remade the "Early Church."  It included information with lots of foot notes for from the years before Constantine to later rules that effected the role of the church in the Empire. It also dealt  with the actually heresies and different groups within the Church that were there at the time.  There is of course many things on Arianism and the different Church councils of the time as well as actual writings from people at the time.  And it includes plenty of information on what the different heretics groups believed so people can see that they were nothing like what preacher X says that they believed.