Monotheistic religions hold in common the belief that there is only one God and therefore only one divine essence. The identity of this God differs from religion to religion, but fundamental agreement exists that there is only one God, no matter who He happens to be.

Christian monotheism, however, does differ from other monotheistic faiths in its understanding of how this essence is possessed by God, even though Christianity agrees that there is only one God and only one divine essence. Other monotheistic faiths teach that the one divine essence belongs to only one divine person. Historic, biblical, orthodox Christian monotheism, however, says that the one divine essence belongs equally to three distinct divine persons. God is not merely Allah, for example; He is Father, Son, and Holy Spirit.

In other words, Father, Son, and Spirit are all fully divine, possessing identical divine attributes. Being fully equal, none is more or less God than the other. And this is our confession based on much biblical evidence.

First, some theologians have noted the Old Testament use of Elohim, one of the Hebrew terms translated into English as “God.” Though it is often used as a singular in Hebrew grammar, Elohim is actually plural in form. So, some have seen in the word itself a hint of plurality in God. It should be noted that the mere word itself does not necessitate a reference to divine plurality, and it would be insufficient by itself to give us a God who is both one and many. Its use, however, is congruent with the doctrine of the Trinity.

Psalm 110, which makes a distinction between the “LORD” (Yahweh) and the “Lord” (Adonai), also points us in the direction of Trinitarianism. There is an allusion to two divine persons, and Jesus brings this out in His use of the text to show His opponents that He is far more than a mere human son of David (Matt. 22:41–46).

Although there are various hints at God’s Trinitarian existence in the Old Testament, we do not get a full-orbed revelation of the Trinity until the New Testament. John 1:1–18, for example, is a clear teaching on the deity of Christ, the Word who in the beginning was God and was with God. There are also texts wherein the three persons are so closely associated so as to imply that all three are fully divine (for example, 2 Cor. 13:14). Clearly, the Bible assumes and teaches that God is triune.

True God is one. But the trinity is real. It is Biblical.

Romans 11:33-36 is a masterful presentation of the doctrine of God that affirms such things as His wisdom, knowledge, inscrutable judgments, and more. Because the doctrine of God is foundational to all of our theology, we are going to take a short break from our study of the book of Romans to look at various aspects of theology proper, or the doctrine of God. Volume 2 of Dr. R.C. Sproul's teaching series Foundations will guide our study.

We begin with a brief look at the Lord's existence. Both the natural world and Scripture testify that our Creator exists (Ps. 19; Rom. 1:18-32), but what kind of being is He? We learn from the Word of God that our Creator is a Trinity.

"One in essence, three in person" is the most concise definition of the doctrine of the Trinity. The Christian faith is not polytheistic, confessing many individual gods, each with its own peculiar divine nature. The Christian faith is not unitarian, confessing that the one divine nature is possessed only by a single person or a single acting subject. Instead, the Christian faith says that three distinct persons are the one divine nature in its entirety. The Father possesses all that makes God who He is; the Son possesses all that makes God who He is; and the Spirit possesses all that makes God who He is. We do not worship three gods, each of whom has his own power, his own intelligence, and so on. Instead, we worship three persons who hold in common the same power, the same intelligence, and so on.

Many biblical passages teach the Trinitarian existence of God. Among the most famous of these is John 1:1-18, which says that the Word—the Son—is both identical to the Father in some way and distinct from Him in another. Another important passage, Matthew 28:18-20, commands us to baptize people in the name of the Father, Son, and Holy Spirit. Such a text shows us that within God Himself there is both a unity between Father, Son, and Holy Spirit (one name) and a distinction (three subjects or persons).

We do not have a logical contradiction here because God is both one and three at the same time, but He is not one and three in the same sense. The three divine persons are distinct in terms of their personal relationships to one another, but not in their essence. All of them are the being of God. They do not have an independent existence—you could not take away any of the three persons and still have God. Rather, the three persons subsist within the one divine nature, coequal in terms of their shared essence.

Coram Deo

The doctrine of the Trinity helps to remind us that our God is not a needy being. God did not create us because He was lonely or because He needed someone to love. From all eternity, Father, Son, and Holy Spirit have existed in personal relationship with one another. He lacked nothing before creation, and He depends on nothing in creation. Because He is self-sufficient, we can be confident that He can provide all that we need, and that He can do so for all eternity.