Ethiopia is one of the well-known countries in the Bible. Since the time of Queen of Sheba who visited King Solomon in Jerusalem (Mt. 12: 42), the country practised monotheism and accepted the Old Testament. It was at the time of her son, Emperor Minilik I (1000 BC) that the Ark of the Covenant was brought to the country. Since then, Ethiopians used to travel to Jerusalem to worship the one true God with Israelites. Therefore, some Ethiopians were able to be present in the Holy City on the day of Pentecost. One of the Ethiopians, who travelled to Jerusalem in AD 34, just a few months after the ascension of our Lord and Saviour Jesus Christ, was the eunuch, treasurer, of Queen Candace of Ethiopia. On his return journey from Jerusalem where he worshipped the one true God he became a Christian baptised by Philip the Apostle (Acts 8: 26-39). Then, he returned home to Ethiopia and commenced evangelising his fellow citizens, the people of Ethiopia. This book illustrates how the Roman Catholic missionaries devastated the ancient Christian societies in Ethiopia (the Ethiopian Orthodox Tewahido Church). This examination shows why the Ethiopian Orthodox Tewahido Church was left exposed to repeated Islamic attacks and the offensive mission of Chalcedonian missionaries against the aforementioned Church. The later caused civil war and Christological controversies that brought the internal disintegration of Christian Ethiopia, which lasted for more than two centuries.