Most Christians are willing to recognize that modalism is heresy; yet at the same time, what passes for a rejection of modalism today is so lacking that many closet modalists can seemingly vindicate themselves of being modalists ( in name, at least) while still holding to the same fundamental doctrines as those who openly hold to modalism.
This is because it has become acceptable to respond to modalism by stating that the persons of the Trinity are not identical to each other; the Father is not the Son, nor the Son the Father, and neither of them is the Holy Spirit. And yet, this does not exclude all forms of modalism, nor does it address the fundamental underlying tenet of modalism that the Father, the Son, and the Holy Spirit are all one person.
As noted in Equivocation Over the Term “Person”, many modern Christians effectively state their belief in trinitarianism as a belief in one person (the Trinity or the essence) who is three persons (the Father, the Son, and the Holy Spirit). This is almost always done by using a synonymous word for “person” in respect to the Trinity as a whole, such as “being”; a word vague enough that it can be used either for an abstract essence or for an individual person, which in most cases like this, is used to mean the latter (a fact often betrayed by the use of singular personal pronouns such as “he” for the “being”). Others will use terms such as “reality”, “thing”, or some other term to describe the person who they conceive of as being three persons; yet using a different word in place of “person” hardly alleviates the problem, since what we ought to primarily be concerned with is not the modes of expression people employ (although these are important), but what is meant by them.
Since, then, the fundamental problem posed by modalism is that it conceives of God as a single individual who somehow is the Father, Son, and Spirit, if we merely require someone to affirm that there is some kind of distinction between “Father”, “Son”, and “Spirit” such as that they are not totally synonymous with each other, we have failed to address the primary issue. Many modalists are willing to affirm such a distinction. While they believe there is only one divine individual, they are also willing to affirm that the names “Father”, “Son”, and “Spirit” refer to three things that are not totally interchangeable with each other.
This distinction may be as shallow as the names themselves; it may extend to seeing them as signifying historically distinct modes by which the one individual manifests himself to the world; or they may view each name as signifying a distinct mode of subsistence within a single individual. Others would view them as effectively signifying different parts of this one individual. All these notions are blasphemous and false; yet by merely accepting the affirmation of some difference between “Father”, “Son”, and “Spirit” as being enough to clear a person of being a modalist, we will have let most modalists pass themselves off as trinitarians with little difficulty.
Even Sabellius himself was willing to say that there were three distinct “personas”, after all. Other early modalists would also try to affirm that while in their minds “Father” and “Son” were the same individual, only the Son died, not the Father. Yet today, it seems we have pushed the threshold of what constitutes trinitarianism so low that those who call the Trinity as a whole a single person, and a single individual, are not regarded as modalists. While they are not given the label they deserve, the underlying beliefs are fundamentally the same. Just as the Sabellians of old taught, if “Father” and “Son” are the same individual, then the Father became man and died on the cross. And yet today this view is tolerated, so long as the person specifies that it was the mode of “Son” that died, not the mode of “Father”.
To really be cleared of modalism, a person must be willing not only to to say that the Father, Son, and Holy Spirit are somehow distinct, but that They are distinct as three individuals, three real persons. A modalist can say that they are somehow distinct, especially if that modalist is willing to equivocate over the term “person”, using it to mean something less than a really distinct individual. A trinitarian must affirm that there are in reality three distinct individuals, the Father, the Son, and the Holy Spirit.
If we wish to guard against semi-modalism, we must go farther still. A semi-modalist does affirm that there are really three distinct persons; however, the semi-modalist believes these three persons to be one person as well. This view is nonsensical; yet, it is held by many, more often than not as an unconscious inconsistency in their own thinking. Yet, some would venture to hold such a view consciously, being willing to say that they believe in one person who is three persons, and really mean “three persons” by those words. The only way to guard against such an error is to not only require a confession of three distinct persons, three distinct individual realities, but to also require a denial that those three are one person or individual reality.
Thus the ancient Macrostich says:
“3. Nor again, in confessing three realities and three persons, of the Father and the Son and the Holy Ghost according to the Scriptures, do we therefore make Gods three; since we acknowledge the self-complete and unbegotten and unbegun and invisible God to be one only, the God and Father (John 20:17) of the Only-begotten, who alone has being from Himself, and alone vouchsafes this to all others bountifully.”
“And those who say that the Father and Son and Holy Ghost are the same, and irreligiously take the three names of one and the same reality and person, we justly proscribe from the Church, because they suppose the illimitable and impassible Father to be also limitable and passable through His becoming man. For such are they whom Romans call Patripassians, and we Sabellians. For we acknowledge that the Father who sent, remained in the peculiar state of His unchangeable Godhead, and that Christ who was sent fulfilled the economy of the Incarnation.”
It is not enough that someone be willing to say the words “three persons”; they must be willing to affirm that they mean that in the sense it is intended, that they believe in three distinct individual realities, not merely three modes or manifestations termed “persons”. Likewise, a trinitarian must be willing to affirm that there is only three persons; this guards against the semi-modalism that imagines a fourth distinct individual (or person) who is the three persons of Father, Son, and Spirit.