How Do We Know That God Is One In Three Persons (And Not Four Persons)?

Jason writes to ask:

From a Christian perspective, how do we know that God is three persons (and not four or more)? Is it possible, from a Christian perspective, that God has only chosen to reveal three persons (but that God is four or more persons but that he has chosen not to reveal the other person/s)? Someone asked me how do I know that God is only three persons (and not four or more) and I have struggled to get a clear answer since.


This is an important question for two reasons: first, because it asks about one of the essential doctrines of the Christian faith, one of of those doctrines that distinguishes Christians from non-Christian religions, e.g., paganism, Judaism, and Islam. Second, it is an important question because it implicitly asks how Christians know anything about their faith? Our late-modern culture suspects that everything is just a social construct, i.e., that some people got together somewhere and decided to say x and not y but for no particular reason that is inherent to the doctrine but just as an exercise of power politics, to include this group and to exclude that.

Christianity Is Not A Mere Social Construct

Christianity is not an arbitrary religion or a human, social construct that needs to be deconstructed. It is not a product of nature or natural religion, though we certainly confess that God has revealed himself in nature (Rom 1:19–20; 2:14–15). Some of the cults (sects), e.g., the Jehovah’s Witnesses (a false religion formed in the 19th century) allege that the doctrine of the Trinity was invented at the Council of Nicea. Conspiracy theorists such as Dan Brown play on such fears and suspicions.

Nothing could be farther from the truth. The doctrine that God is one in three persons is revealed in holy Scripture, in the Word of God, and that is how we know that God is one in essence (or substance) and three in person. Our Lord Jesus said, “Your Word is Truth” (John 17:17).

In the Heidelberg Catechism (1563), the Reformed Churches confess their understanding of God’s Word:

25. Since there is but one Divine Being, why do you speak of three persons: Father, Son and Holy Spirit?

Because God has so revealed Himself in His Word, that these three distinct persons are the one, true, eternal God.

That God is one, in three co-eternal, consubstantial, distinct persons is a matter of special (as distinct from natural) divine revelation. It is a Christian conviction that God says what is, i.e., he tells the truth.

The Bible Says So

God is not one person nor is he four. How can Christians be so certain? Because God’s Word is clear. It gradually reveals that God is one (Deut 6:4) but he is so in multiple persons. As the resources below explain in much greater detail, the Scriptures themselves lead us to see that God has always revealed himself to be one, in multiple persons but that God is one in only three persons was made explicit in the New Testament. Our Lord Jesus commanded us to baptize in the name of the Father, the Son, and the Holy Spirit (Matt 28:19). The New Testament only mentions three persons, not four and not one.

The church did not invent the doctrine of the Trinity at the Council of Nicea. The early Christian church recognized right away, in the early 2nd century, that God had revealed himself in Scripture to be one in three, distinct, co-eternal, consubstantial persons: Father, Son, and Holy Spirit. The earliest Christian teachers used that language. The early 3rd century Christian theologian Tertullian, in Carthage, gave us the term “Trinitas” but he was merely recognizing what Christians were already saying and what the Word of God teaches.

At Nicea (AD 325) and again at Constantinople (AD 381) and again at Ephesus (AD 431) and Chalcedon (AD 451) We did clarify our doctrine of the Trinity and our doctrine of the two natures of Christ. All of that was wonderfully summarized in the Athanasian Creed, probably from the 5th century. That creed is linked below and will repay study tenfold.

No, it is not possible that God is really one person or four persons. The God revealed in Scripture is not a liar. It is true that we cannot know God as he is, in himself. As creatures we can only know what creatures are able to know. Yet, God is more than capable of revealing himself truly to finite creatures such as we. It is true that we cannot know God’s attributes, e.g., his holiness or his immensity as he knows them or as they are in himself but we are able to understand what we need to know for our salvation and for the Christian life. This is what Scripture does for us: through it God reveals to us what we can and must know.

Three Offices And Three Persons

We able to know and understand that the Father is God, the Son is God, and the Holy Spirit is God because Scripture reveals that each of the persons of the Trinity is true God and consubstantial with the other persons and yet personally distinct. The Father is not the Son or the Spirit. The Son is not the Father or the Holy Spirit and the Spirit is neither the Father nor the Son. There are no other persons of the Trinity and no fewer than three. Though all the persons of the Trinity are co-active in creation, providence, and redemption, we may think generally of creation and providence as the office of the Father, of the revelation of God and salvation as the office of the Son, the Word, and the application of redemption and sanctification as the special work of the Spirit. What left is there to do for some imaginary fourth member of the Deity?

As Christians, we cannot be Unitarians or Modalists, confessing that God Only seemed to be the Father, or the Son, or the Spirit—as if God put on a Father mask, a Son mask, and a Holy Spirit mask. That is rationalism that seeks to go behind Holy Scripture. As Christians, we may not do that. Indeed, it is not possible. Our Lord Jesus spoke of his Father and ours. That was not just a way of talking. Our Lord Jesus claimed to be God the Son incarnate, not just some temporary manifestation of God. The Spirit is always treated in Scripture as a distinct, co-equal person of the Trinity.

The doctrine of the Trinity is biblical doctrine and it is universal Christian truth. Of course a short essay like this cannot explore all the truths there are to tell about the Trinity. The resources below will help you go further.

©R. Scott Clark. All Rights Reserved.


Heidelberg Reformation Association
1637 E. Valley Parkway #391
Escondido CA 92027
The HRA is a 501(c)(3) non-profit organization

Subscribe to the Heidelblog today!