The doctrine of the incarnation is fundamental to orthodox Christianity. If this doctrine is denied, the whole structure of Christian faith, theology and spirituality collapses. Yet for many the very notion that God became a human person is impossible to believe. This sense of incredulity is not confined to our secular, post-Enlightenment age. From the very beginning, there have been those who have rejected the claim that Jesus Christ was true God and true man, and it took a series of fierce disputes and controversies before the Church finally defined the doctrine of the incarnation.