The theme of union with God (Father, Son, and Holy Spirit) is a common thread that runs throughout the history of great Christian devotional writing. Every stream within the Great Tradition has reflected on the meaning and means of union with God through Christ, as well as his call to, “…abide in me.”
Trinitytide worship is pointed towards the kind of life that reflects the love of the Trinity, the journey “…to glorify God and enjoy Him forever.” Growth in grace is a trek towards home, a return to the source and sustainer of life.
“The aim of man’s life is union (henosis) with God. This participation takes man within the life of the three Divine Persons themselves, in the incessant circulation and overflowing love which courses between the Father, the Son, and the Spirit, and which expresses the very nature of God. Here is the true and eternal bliss of man. Union with God is the perfect fulfillment of the “kingdom” announced by the Gospel, and of that charity or love which sums up all the Law and the Prophets. Only in union with the life of the Three Persons is man enabled to love God with his whole heart, soul, and mind, and his neighbor as himself.”
-Fr Lev Gillet (1893-1980) in Orthodox Spirituality: An Outline of the Orthodox Ascetical and Mystical Tradition