The Doctrine of the Trinity
As taught in the Reformed / Presbyterian tradition
Understanding the ontological equality and economic distinctions of the Father, Son, and Holy Spirit.
The doctrine of the Trinity is the cornerstone of Christian theology, answering the most fundamental question of the faith: "Who is the God whom we worship?" Within the Reformed tradition, this is not merely a philosophical puzzle to be solved or a mathematical contradiction to be explained away, but the ontological foundation of all redemptive history. The Reformed faith asserts that God is one in essence and three in person—Father, Son, and Holy Spirit. This subtopic addresses the internal life of the Godhead (the ad intra relations) and how that life is manifested toward the creation (the ad extra operations). In the Reformed perspective, theology proper—the study of God Himself—must begin and end with the Trinity, for to speak of God is to speak of the Triune Lord of the Covenant.
By the end of this lesson
- **Identify** the essential distinctions between the three Persons of the Godhead while maintaining the absolute unity of the divine essence.
- **Distinguish** the Reformed "Classical Trinitarianism" from common heresies such as Modalism (Sabellianism), Arianism, and Tritheism.
- **Explain** the significance of the "singular name" in the baptismal formula of Matthew 28:19 as it relates to the unity of God.
- **Articulate** the roles of the Father, Son, and Holy Spirit in the "Economic Trinity" (how they act in history) versus the "Ontological Trinity" (who they are in themselves).
- **Trace** the development of Trinitarian language through the Athanasian Creed and the Westminster Shorter Catechism.
- **Defend** the deity and personality of the Holy Spirit against modern unitarian or "force-based" interpretations.
- **Apply** the doctrine of the Trinity to the Christian life, specifically in the areas of prayer, worship, and the structure of the covenant community.
- **Compare** the Reformed view of the "Filioque" clause and the eternal generation of the Son with other major Christian traditions.
Scripture
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