Gregory of Nazianzus (Greek: Γρηγόριος ὁ Ναζιανζηνός Grēgorios ho Nazianzēnos; c. 329 – 25 January 390), also known as Gregory the Theologian or Gregory Nazianzen, was a 4th-century Archbishop of Constantinople, and theologian. He is widely considered the most accomplished rhetorical stylist of the patristic age. As a classically trained orator and philosopher he infused Hellenism into the early church, establishing the paradigm of Byzantine theologians and church officials.
Read about Gregory of Nazianzus in Wikipedia