Trinity Sunday is the first Sunday after Pentecost in the Western Christian liturgical calendar, and the Sunday of Pentecost in Eastern Christianity. Trinity Sunday celebrates the Christian doctrine of the Trinity, the three Persons of God: the Father, the Son, and the Holy Spirit. Anglican, Reformed (Continental Reformed, Presbyterian, Congregationalist), and Methodist.
History
thumb|The Holy Trinity by St. [[Andrei Rublev, using the theme of the "Hospitality of Abraham." The three angels symbolize the Holy Trinity, which is rarely depicted directly in Byzantine art.]]
In the early Church, no special Office or day was assigned for the Holy Trinity. When the Arian heresy was spreading, the Fathers prepared an Office with canticles, responses, a Preface, and hymns, to be recited on Sundays. In the Sacramentary of Gregory the Great there are prayers and the Preface of the Trinity. During the Middle Ages, especially during the Carolingian period, devotion to the Blessed Trinity was a highly important feature of private devotion and inspired several liturgical expressions. Sundays are traditionally dedicated to the Holy Trinity.
In the traditional Divine Office, the Athanasian Creed (Quicumque vult) is said on this day at Prime. Before 1960, it was said on all Sundays after Epiphany and Pentecost which do not fall within Octaves or on which a feast of Double rank or higher was celebrated or commemorated, as well as on Trinity Sunday. The 1960 reforms reduced it to once a year, on this Sunday.
In the 1962 Missal, the Mass for the First Sunday After Pentecost is not said or commemorated on Sunday (it is permanently impeded there by Trinity Sunday), but is used during the week if the ferial Mass is being said. The Lutheran Book of Worship, Lutheran Worship, and Lutheran Service Book specify this.
Thomas Becket (1118–1170) was consecrated Archbishop of Canterbury on the Sunday after Pentecost (Whitsun). His martyrdom may have influenced the popularity of the feast in England. This observance spread from Canterbury throughout the whole of western Christendom. It is in the Historical Documents section of the 1979 Book of Common Prayer (Episcopal Church), but its use is not specifically provided for in the rubrics of that prayer book.
Parishes with an Anglo-Catholic churchmanship follow a calendar where Corpus Christi is observed on the following Thursday, or in some cases the following Sunday.
Methodism
In traditional Methodist usage, The Book of Worship for Church and Home (1965) provides the following Collects for Trinity Sunday: