Eastern Orthodox thought about God is rooted in the experience of repentance, spiritual growth, and liturgical communion. The Greek Church Fathers, whose work provides the foundation for Orthodox theology, articulated this experience in terms of a comprehensive understanding of God as the Good, meaning that he is both the source of all goodness and the proper object of all human desire. This Element traces the line of thought that leads from the experience of God as it is understood in Orthodoxy to its philosophical articulation. Among the topics covered are the essence-energies distinction, the Trinity, the Incarnation, time and eternity, divine foreknowledge and human freedom, and the problem of evil.