At our Baptism the entire Trinity took possession of our entire being (Gospel); hence our lifelong necessity of practical true faith in the presence of the Trinity in our souls, as our defence against "all misfortunes" (Prayer); the necessity of being ever conscious in our prayers that we are the adopted "sons of the Father," " co-heirs with Christ," and "temples of the Holy Ghost"; the necessity of shunning mortal sin, which automatically exiles the Trinity from our souls.
The offering of the Mass to the Trinity (Introit, Offertory) makes the offering of our lives (Secret, Communion) acceptable and pleasing. This offering of the Mass and of ourselves brings Divine help to body and soul (Postcommunion).
On this feast we should renew our Baptismal vows: "I renew my Baptismal vows. I renounce Satan and all his works and all his pomps. I take Jesus Christ for my Model and my Guide, and I promise to be faithful to Him unto the end of my life. (Pater, Ave, Gloria). Under the newer rubrics of the Mass, the I Sunday is not ordinarily commemorated, but many Traditional Catholic orders are now making the commemoration, while Last Gospel is Proper Gospel of the I Sunday.