Christians celebrate Trinity Sunday to honor and reflect on the mystery of one God in three Persons—Father, Son, and Holy Spirit. Trinity Sunday calls us to focus on who God is and how He works in the world and in our lives.
Trinity Sunday (also called Holy Trinity Sunday) is a day commemorated on the Sunday following Pentecost to emphasize the Trinity—Father, Son, and Holy Spirit. In the Western church calendar, this Sunday occurs on the eighth Sunday following Easter (since Pentecost Sunday falls on the seventh Sunday after Easter) in May or June of each year. While the word “Trinity” is not explicitly found in Scripture, the concept is clearly revealed throughout both the Old and New Testaments. The observance of Trinity Sunday, which originated in the fourth century, was a response to false teachings that denied Christ’s divinity and was later formally added to the church calendar, helping believers maintain a proper understanding of God’s nature. Historically, creeds like the Athanasian Creed emphasized the equality and unity of the three Persons without confusing or dividing them. Today, Trinity Sunday reminds Christians that God exists in perfect oneness and relational community, demonstrates His glory and majesty, and continues to work in the world through creation, the life and sacrifice of Jesus, and the empowering presence of the Holy Spirit. It calls the church to worship a God who is both transcendent and personal, inviting believers to live in relationship with Him and with one another. Observing Trinity Sunday helps deepen our understanding of God and His work in the world and in our lives.
Trinity Sunday originated in the fourth century as a response to the erroneous teaching of Arius who taught Jesus was a created being and thus denied the deity of Christ. The famous Council of Nicaea in 325 affirmed the biblical view of Jesus as both fully God and fully human, as well as the belief in the Triune God. Though celebrated for some time prior, Trinity Sunday was officially added to the church calendar by Pope John XXII (1316-1334).
In addition, the Athanasian Creed has served as part of the reading in some mass ceremonies in the past, though this is not common today. It reads, in part, "We venerate one God in the Trinity, and the Trinity in oneness; neither confounding the persons, nor dividing the substance; for there is one person of the Father, another of the Son, and another of the Holy Spirit; but the divine nature of the Father and of the Son and of the Holy Spirit is one, their glory is equal, their majesty is coeternal."
Trinity Sunday helps the church to emphasize the proper understanding of Father, Son, and Spirit, and reminds us that God exists in both perfect oneness and community. He is perfect in every way, transcending all creation, sending Jesus to live among humanity, and empowering believers by the Spirit today.