As Christians, we confess that there is one God who eternally exists in three distinct persons: Father, Son, and Holy Spirit.
The three persons of the Trinity are equal in power and glory, are co-eternal, and are of the same essence (Ousia in Greek).
The Father is God, the Son is God, the Spirit is God, but the Father is not the Son, the Son is not the Father, nor is the Spirit the Father or the Son.
The three persons of the Trinity also have unique functions, and relate to each other in unique ways. As a result, we can speak about the Trinity in two ways: the “Ontological Trinity” and the “Economic Trinity.”
“Ontological” has to doing with “being.” So, to speak of the Ontological Trinity is to explain who God is, and who the three persons of the Godhead are.
The major ecumenical councils of the church, such as Nicaea and Chalcedon, focused on the ontological nature of the persons of the Trinity, and affirmed that Jesus, the Son, is very God of very God, and that the Holy Spirit is not an impersonal force, but is, indeed, God.
So, to speak about the Trinity ontologically, is to affirm both the divine nature and the unique personhood of the three persons of the Trinity.
“Economic” has to do with action, roles, and function: what God (and each person of the Godhead) does.
So, when we take an economic view of the Trinity, we are talking about the things which the Father does, or which the Spirit does, which are unique to that person of the Godhead.
For example, it is the role and function of the Holy Spirit to perform the sealing and sanctifying functions of God in the life of a believer.
Jesus, the divine Son, uniquely took on human flesh, came to Earth, lived a sinless life, and died on a cross for our redemption.
The Father sent the Son, the Son submitted to the Father and obeyed the Father, the Father and the Son sent the Spirit. The Spirit glorifies and points to the Son. The Son glorifies the Father. The Father exalts the Son. The Son ever lives to make intercession for us. The Spirit indwells believers, reminding them of what the Son said, and bringing about conviction of sin, righteousness, and judgment.
One important application of these principles, is the understanding that economic actions, such as submission, leadership, and difference of roles, does not diminish or take away from a person’s ontological identity, value, dignity, or identity.
This is communicated explicitly in Philippians 2, where we are told that Jesus, although he was equal with the Father, as God (ontologically), did not regard equality with [the Father] (economically) something to be grasped, but emptied himself, taking the form of a servant, being born in the likeness of men, and humbled himself in obedience, even to the point of death on a cross.
The point here is that Jesus’ economic activity did not detract from his ontological nature.
A point of application is made in the New Testament, in the complementary roles of men and women in the church. Though men are called to teach and exercise authority in the “household of God” (1 Timothy 3:15), this does not diminish or take away from the ontological equality of men and women as human beings, and as children of God, but is rather a matter of economic function. If this is true of the Trinity (and clearly it is), then it should not surprise us that it is true in the “household of God,” acted out by those who reflect His image to the world.
For more on this, check out this discussion of 1 Timothy 2:8-15, which I had with my wife, Rosemary, for our church’s weekly Sermon Extra video: