The Bible teaches that there is only one true and eternal God, yet this one God eternally exists in three distinct persons: the Father, the Son, and the Holy Spirit. While this doctrine surpasses human understanding, it is the foundation of the Christian faith, as each person of the Trinity is revealed as fully God, sharing the same divine essence, power, and eternity.
The Scriptures consistently proclaim that there is but one living and true God, yet they simultaneously reveal that within this one infinite Being, there are three subsistences: the Father, the Word (or Son), and the Holy Spirit. As confessed in the 1689 LBCF Ch.2 §3, these three are of one substance, power, and eternity, sharing the undivided divine essence. This truth is anchored in the Old Testament's witness to the unity of God (Deuteronomy 6:4) and confirmed by Christ's explicit command to baptize in the singular name of the three persons (Matthew 28:19). We affirm that God is more than we can fathom; we are more sinful than we dare believe, yet in the economy of this triune grace, we are more loved in Christ than we ever dared hope.
Though they are one in essence, the persons of the Trinity are distinguished by their internal relations and their external operations toward us. As noted in the Belgic Confession Art. 9, the Father is our Creator, the Son is our Savior and Redeemer, and the Holy Spirit is our Sanctifier. Scripture demonstrates this distinct action, such as during the incarnation where the Holy Spirit overshadows Mary and the power of the Highest dwells upon her to bring forth the Son (Luke 1:35). This distinction is not a division of God but a beautiful revelation of how God relates to His creation, inviting us into communion with Himself through the work of the Son and the indwelling of the Spirit.