By the eleventh century there is a feast of the Trinity being celebrated on the first Sunday after Pentecost, which quickly gained in popularity. The feast did arouse opposition from the pope but eventually became a feast of the universal Church in 1334. Speculation exists that this feast could only have gained popularity in a time when the liturgical life of the Church was less than it could be. If all liturgies were seen as involving the community in the life of God, Father, Son and Spirit, the appeal for such a feast would have been significantly lessened. Be that as it may, for our own time the feast does serve a vital purpose.
Western theology tends to be very abstract and concerned with strong philosophical categories.
This is particularly true in our explanations of the Trinity. While solid theological examination is necessary for the Church, it can to something less than a Spirit-filled celebration. The feast provides a balance to this intellectual trend. The liturgy focuses on the activity of the Divine Persons and our being drawn into it. He sees the Son whom He loves.