With the descent of the Holy Spirit on Pentecost Sunday, the Church was born. Thus, it is appropriate that, on the very next Sunday (this Sunday), we celebrate one of the central mysteries of our faith: the Holy Trinity.
Trinity Sunday, also known as Holy Trinity Sunday, is celebrated a week after Pentecost Sunday in honor of the most fundamental of Christian beliefs—belief in the Holy Trinity. We can never fully understand the mystery of the Trinity, but we can sum it up in the following formula: God is three Persons in one Nature. The three Persons of God—Father, Son, and Holy Spirit—are all equally God, and They cannot be divided.