John of Damascus (PDF includes Hilary of Poitiers)
John of Damascus is considered to be one of the last of the Church Fathers. There is very little that is known regarding his life. John spent a period of time in the courts of the Muslims as a counsellor and it was here he was able to learn their teachings first hand. He is famous for his works against Islam which does not pull any punches with the questionable claims of the Koran.
An Exact Exposition of the Faith
Book 4 (Latin/Greek)