The fundamental dogma, on which everything in Christianity is based, is that of the Blessed Trinity in whose name all Christians are baptized. The feast of the Blessed Trinity needs to be understood and celebrated as a prolongation of the mysteries of Christ, and as the solemn expression of our faith in this triune life of the Divine Persons, to which we have been given access by Baptism and by the Redemption won for us by Christ. Only in heaven shall we properly understand what it means, in union with Christ, to share as sons in the very life of God.
The feast of the Blessed Trinity was introduced in the ninth century and was only inserted in the general calendar of the Church in the fourteenth century by Pope John XXII. But the cultus of the Trinity is, of course, to be found throughout the liturgy. Constantly the Church causes us to praise and adore the thrice-holy God who has so shown His mercy towards us and has given us to share in His life.
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