Trinity Sunday - What is it?

TL;DR:

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.

what does the bible say?

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.

from the old testament

Though the term Trinity is not mentioned in the Bible, the doctrine is found throughout Scripture, especially in the New Testament. Readings used in the church on Trinity Sunday include Deuteronomy 4:32-34, 39-40; Psalm 33:4-5, 6, 9, 18-19, 20, 22.

from the new testament

Jesus gave His disciples the Great Commission: "Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit" (Matthew 28:19). He emphasized one baptism into one name—Father, Son, and Spirit.
While God the Father is affirmed clearly throughout the Old Testament and the entire Bible, the New Testament clearly affirms the deity of Jesus (John 1:1, 10:30) and the Spirit by referring to each as God (Acts 5:1-4).
Early in Paul's writings, we also find clear references to all three Persons of the Triune God together. Second Corinthians 13:14 says, "The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all." First Thessalonians 1:3-5 adds, "remembering before our God and Father your work of faith and labor of love and steadfastness of hope in our Lord Jesus Christ. For we know, brothers loved by God, that he has chosen you, because our gospel came to you not only in word, but also in power and in the Holy Spirit and with full conviction."

implications for today

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.

understand

Trinity Sunday celebrates God as Father, Son, and Holy Spirit.
Trinity Sunday originated in the fourth century to defend the divinity of Christ.
Trinity Sunday reminds believers of God’s work in the world and calls them to worship and deepen their relationship with Him.

reflect

How does reflecting on God as Father, Son, and Holy Spirit shape your understanding of His character and work in your life?
How do you recognize and worship God in the fullness of the Trinity?
How does recognizing the unity and equality of the three Persons of God influence your faith and trust in Him?

engage

How does observing Trinity Sunday help us grow in understanding and devotion to God?
Why was it important for the early church to defend the divinity of Christ through celebrations like Trinity Sunday?
How can we practically live out the relational and communal aspects of God’s nature in our interactions with others?