Lesson 18 – The Trinity and Baptism

Why do Christians baptize in the name of the Trinity? Or to put it another way: Does it really matter what you SAY at a baptism? The answer is: yes – in fact, it makes all the difference in the world! Why is that? What is the connection between Baptism and the Trinity?

Course Reading

Summa Theologiae III, q. 66, a. 5 | St. Thomas Aquinas

Summa Theologiae III, q. 66, a. 8 | St. Thomas Aquinas

Excerpt from the Summa Theologiae III, q. 66:

Baptism receives its consecration from its form, according to Eph. 5:26: "Cleansing it by the laver of water in the word of life." And Augustine says (De Unico Baptismo iv) that "Baptism is consecrated by the words of the Gospel." Consequently the cause of Baptism needs to be expressed in the baptismal form. Now this cause is twofold; the principal cause from which it derives its virtue, and this is the Blessed Trinity; and the instrumental cause, viz. the minister who confers the sacrament outwardly. Wherefore both causes should be expressed in the form of Baptism. Now the minister is designated by the words, "I baptize thee"; and the principal cause in the words, "in the name of the Father, and of the Son, and of the Holy Ghost." Therefore this is the suitable form of Baptism: "I baptize thee in the name of the Father, and of the Son, and of the Holy Ghost."

Course Listening

An Introduction to the Trinity and to the Mystery of Jesus Christ | Fr. Dominic Legge, O.P.

The Trinity at Christ's Baptism and the Institution of the First Sacrament | Fr. Dominic Legge, O.P.