I could not direct you to the perfect source to answer that question, but I find these sites helpful:
Edward Gibbon's Decline and Fall of the Roman Empire - Try chapters 15 and 16 and through to ch 21 ... Also sprinkled throughout ....
http://www.ccel.org/g/gibbon/decline/volume1/index.htm Also check into the Christian Classics Ethereal Library, which is a huge repository of Christian literature through the ages .... This is where the Gibbon history text resides as well
http://www.ccel.org Finally, wikipedia "History of Christianity"
http://en.wikipedia.org/wiki/History_of_Christianity