In this lecture, Fr. Matthias Shehad concludes his series on the origins of the Orthodox Church, tracing its foundation from Pentecost through key historical events and ecumenical councils. He discusses the development of early church structure and doctrine, including the councils of Nicaea, Constantinople, Ephesus, and Chalcedon, highlighting theological disputes such as Arianism and Nestorianism and their resolutions.

Fr. Matthias explains the 1054 schism between the Orthodox and Roman Catholic churches, emphasizing the later additions to the Nicene Creed and differing views on papal authority. He then explores the 16th-century Protestant Reformation led by Martin Luther, focusing on issues like indulgences, purgatory, and sola scriptura, and contrasts Protestant reforms with Orthodox theology and tradition.

This presentation provides a historical overview of how major Christian denominations arose from the original Orthodox faith and theological controversies shaping them.