What's the Difference between the Ontological and the Economic Trinity?

Do you know the meaning of the word Trinity? In all likelihood, most of those reading this are familiar with this word and its meaning in theology. But what if I were to ask you to distinguish between the "ontological Trinity" and the "economic Trinity"? If I said, "Please describe for me the difference between the ontological Trinity and the economic Trinity," could you do it? The distinction is very important.

Ontology is the study of being. When we talk about the ontological Trinity, or as some theologians term it, the "immanent Trinity," we are referring to the Trinity in itself, without regard to God's works of creation and redemption. In the Trinity, there are three persons —the Father, the Son, and the Holy Spirit—who together are one being. The ontological structure of the Trinity is a unity (Deut. 6:4). When we speak of the economic Trinity, on the other hand, we are dealing with the activity of God and the roles of the three persons with regard to creation and redemption.

In terms of the ontological Trinity, the three persons are distinguished by what the Westminster Larger Catechism calls "their personal properties" (WLC 9). It then goes on to define these personal properties: "It is proper to the Father to beget the Son, and to the Son to be begotten of the Father, and to the Holy Ghost to proceed from the Father and the Son from all eternity" (WLC 10). With regard to the economic Trinity, we distinguish among the three persons of the Godhead in terms of their roles in creation and redemption. It is the Father who sends the Son into the world for our redemption. It is the Son who acquires our redemption for us. It is the Spirit who applies that redemption to us. We do not have three gods. We have one God in three persons, and the three persons are distinguished in the economy of redemption in terms of what They do.

In orthodox Christianity, we say that the Son is equal to the Father in power, in glory, and in being. This discussion rests heavily on John 1:1, where we read, "In the beginning was the Word, and the Word was with God, and the Word was God." This verse indicates that the Father and the Word (the Son) are different and are one. In one sense, the Son and the Father are identical. In another sense, They are distinguished. From all eternity, within the ontological Trinity, the Father begets the Son, and the Son is begotten of the Father. From all eternity, God also freely decrees the salvation of yet to be created human beings in what theologians refer to as the "covenant of redemption." This covenant of redemption among the Persons of the Trinity is the eternal foundation for the work of the three Persons in the history of redemption. From all eternity the Father agrees to send the Son, and the Son is willingly sent. The Son doesn't send the Father; the Father sends the Son. So even though the Father and the Son are equal in power, glory, and being, and even though there is no eternal subordination within the ontological Trinity, nevertheless there is a subordination of the Son to the Father in the economy of redemption.

That is what Jesus said in John 5:19–23. He declared: "I don't do anything on My own. I do what the Father tells Me to do. I do what the Father sent Me to do. I watch the Father, and I do what the Father does. The Father is preeminent. The Father is the One to whom I am obedient and subordinate." He even affirmed that He could not do anything of Himself, only what He saw the Father do. Out of His love for the Son, the Father showed Him all the things that He Himself did. Then Jesus stated that the Father would show Him even greater things, so they should expect His works to become greater. In this context, Jesus specifically mentioned the raising of the dead.

This excerpt is taken from R.C. Sproul's commentary on John.