The concept of personhood is crucial for our understanding of what it is to be human. This article considers the ways that Christological debates in the early Church contributed to the emergence of the concept of person. It then suggests that neglect of the theological roots of this concept is the reason why modern definitions of person are unsatisfactory. The latter typically refer to particular properties of the individual, whereas the Trinitarian concept of person is relational. Finally, some ethical implications are drawn from the Christological insight that the person is a fundamental ontological category. In particular, this perspective defends the personhood of those who do not meet the criteria of modern definitions of person. Asking what it means to be human may be as old as humankind itself. Many conflicting views of human nature are on offer. Philosophy of mind has occupied a significant place in the debates. Much of these debates have been shaped by the monism-dualism dichotomy and varieties of these two opposing conceptions. Although challenging arguments abound, and there is much fruitful discussion, the possibility of consensus appears remote, even among those who share the same religious worldview. The time may therefore be ripe for a change of paradigm, a hunt for new insights that could help us to move out of well-worn ruts of discussion. The present article seeks to meet this challenge, by bringing together two intellectual worlds that hardly ever meet: philosophy of mind, and patristic theology. The hope is that this endeavor might indicate fresh directions to explore in our understanding of ourselves, whilst also throwing new light on old debates. The present article focuses on the concept of person, which is key to our understanding of ourselves as human beings. It also played a decisive role in the fierce controversies that arose concerning the Trinity and the Incarnation, early in Church history. The Council of Chalcedon’s declaration is famous for stating that 'Jesus Christ … must be confessed to be in two natures, … being united in one Person.' What is less well known is the fact that the Church Fathers had to significantly advance the concept of person in order to achieve the fine balance of the Christological creed. If we consider this development carefully, and its thoroughly biblical basis, we may better understand what it means to be a person, which has repercussions for human self-awareness.