Athanasius was a prominent early Christian theologian and bishop of Alexandria, known for his strong defense of the doctrine of the Trinity. He played a crucial role in the development of Christian orthodoxy during the 4th century, particularly in opposition to the Arian controversy, which questioned the divinity of Jesus Christ. His most famous work, "On the Incarnation," articulates the belief that Jesus is both fully divine and fully human. Athanasius was exiled multiple times due to his beliefs and conflicts with various Roman emperors. He is recognized as a Doctor of the Church and is celebrated for his contributions to Christian theology, particularly in affirming the Nicene Creed, which established foundational beliefs about the nature of God and Christ. His legacy continues to influence Christian thought today.