Sums up all the observances in the Church's calendar from Advent up until Pentecost. On Trinity Sunday, the Church is reminded of God's eternal nature - they remember that they worship one God in three persons (Father, Son and the Holy Spirit)
The first Sunday after the Pentecost and the only major Holy Day named for a doctrine. Until recently, Sundays were dated after Trinity, a custom believed to have grown in popularity due to St. Thomas Becket, Archbishop of Canterbury.
Trinity Sunday is the first Sunday after Pentecost in the Western Christian liturgical calendar. Trinity Sunday celebrates the Christian doctrine of the Trinity, the three persons of God: the Father, Son, and Holy Spirit. Trinity Sunday is the first Sunday in the second period of Ordinary Time, a period which continues until Advent and is characterised by the use of green as the predominant liturgical colour; however, the colour for Trinity Sunday itself is white.