Semi-modalists such as Cornelius Van Til, who present the Trinity itself as a person who is three persons, naturally use singular personal pronouns for the Trinity, such as “He” and “Him”. This is consistent with their belief that the Trinity is a person; “God the Trinity”, “the triune God”.
Biblical trinitarianism stands at odds with such language, however, since it teaches us to believe in three persons, the Father, the Son, and the Holy Spirit. The titles “one God”, and “only God” are reserved by scripture for the person of the Father alone (see I believe in one God, the Father Almighty.)
This all runs contrary to semi-modalism’s absurd teaching that the one God is a person who is the entire Trinity of three person, and to the convention of using singular personal pronouns for the Trinity as a whole. Doing so clearly implies that the Trinity is a single person (see God’s ‘Preferred Pronouns’ and Do Pronouns Matter?).
Yet some have attempted to justify this convention of language on the grounds that since the actions performed by the persons of the Trinity are single, the persons performing the actions should be referred to with singular personal pronouns. For example, the action of God creating the world was done through His Son and Spirit in such a way not that there were three separate acts of creation, but one, from the Father, through the Son and Holy Spirit. On the basis of each action being singular instead of triple, then, it is argued that we must use singular grammar to reflect this truth; hence justifying the use of singular personal pronouns for for multiple persons of the Trinity together.
This crafty argument falls apart when we make the simple distinction between actions and actors. The actions themselves may in each individual case be singular; but when all three persons of the Trinity are involved in the performing of a given action, as we have spoken of above, there is then a plural number of actors. So while we may (and should) reflect the singularity of such actions by referring to them with grammar that reflects their singularity (such as using singular impersonal pronouns for the actions themselves, such as “They performed it“), it is equally important that we reflect the plurality of actors involved in each single action by using plural personal pronouns for the persons performing the action (“They performed it”).
If we instead were to use singular personal pronouns, we would not be grammatically treating the action as singular, but the actors as singular; which in respect to the persons of the Trinity usually ends in treating all three of Them together as a single person. Such semi-modalistic language carries ultimately heretical implications, which we must avoid if wish to accurately portray the realities the scriptures reveal to us in the way that we speak.