SECOND ARTICLE: WHETHER THE SON IS OTHER THAN THE FATHER

The difficulty arises from Christ's words, "I and the Father are one." The reply nevertheless is that the Son is other than the Father but not another being. This is an article of faith according to the Fourth Lateran Council: "That being (the divine nature) does not beget, nor is it begotten, nor does it proceed, but it is the Father who begets, the Son who is begotten, and the Holy Ghost who proceeds, because the distinctions are in the persons and the unity is in the nature. Although the Father is another, the Son another, and the Holy Ghost another, each is not another being but that which is the Father is the Son and the Holy Ghost, entirely the same, "[330] that is, they are one according to nature and are consubstantial.

This statement of the Council was taken from the writings of St. Gregory Nazianzen.[331] St. Fulgentius, quoted by St. Thomas in his argument sed contra, used the same language. In this way the words of our Lord are safeguarded: "I and the Father are one." The Son and the Father are one; the Son is not another being, although He is other than the Father because He was begotten by the Father.

In the body of the article St. Thomas explains this point by comparing the masculine pronoun, which signifies a person, with the neuter pronoun, which signifies the nature. The reader is referred to the reply to the fourth difficulty, "The neuter gender is unformed, and so conveniently signifies the common essence, whereas the masculine gender signifies a determined person." In the body of the article St. Thomas determines the vocabulary to be used in order to avoid the dangers of Arianism and Sabellianism. To avoid any confusion with Arianism, in speaking of the divine persons we do not use the terms diversity and difference but distinction, because diversity implies a distinction in genus and difference implies a distinction in species. Thus we do not say, the nature is divided into three persons, the person of the Father is separated from the person of the Son, a disparity exists between the persons, nor that the Son is alien to the Father, because the Son is perfectly similar and united to the Father but distinct from Him.

To avoid Sabellianism, we do not say that God is unique, but one in three persons, nor do we say that God is singular or that He is solitary.