What is the Trinity?
Essentially, the Trinity is Who God is.  The Trinity is the one God Who simultaneously expresses Himself to humanity in three distinct ways.  The Trinity is three Persons (Father, Son, and Holy Spirit) distinguishably expressing themselves to humanity as one and the same God.  The doctrine of the Trinity is the uniquely Christian way of speaking about Who God is.

Where does the doctrine of the Trinity come from?
The word “trinity” does not occur in the Bible.  But Christians did not simply invent this doctrine.  The essential affirmations of the doctrine of the Trinity are rooted in the Scriptures.  When certain issues arose which challenged the faith of God’s people, the doctrine of the Trinity took shape as Christians turned to Scripture in order to affirm who God is.

Like all other Christians, Presbyterians believe that the doctrine of the Trinity affirms the oneness of God.  The Old Testament bears witness to this; “The Lord is our God, the Lord alone” (Deuteronomy 6:5), and “I am the Lord your God . . . you shall have no other God’s before Me (Exodus 20:2-3).  Also, in the New Testament, we read, “There is no God but one” (1 Corinthians 8:4).

Presbyterians believe that the doctrine of the Trinity also affirms the Father, the Son, and the Holy Spirit as distinct Persons Who reveal themselves as God.   Many passages from the New Testament mention the Father, Son (or Jesus Christ), and Holy Spirit as co-equals in the work of God.

“Make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit.” (Matthew 28:19)

 “Peter, an apostle . . . to the exiles . . . who have been chosen and destined by God the Father and sanctified by the Spirit to be obedient to Jesus Christ.”

(1 Peter 1:1-2)

“I [the Son] will ask the Father, and He will give you another Advocate, to be with you forever.  This is the Spirit of truth.” (John 14:16-17)

Are the Father, Son, and Holy Spirit three separate gods?
No!  Many non-Christians have falsely assumed that the doctrine of the Trinity teaches tritheism (the belief in and worship of three gods).  Christians do indeed pray in the name of the Father, of the Son, and of the Holy Spirit; and this may appear to non-Christians as though three separate gods are being venerated.

Are the Father, Son, and Holy Spirit three parts of one God?
No!  Many non-Christians have concluded that the doctrine of the Trinity infers a God Who is divisible (a teaching that the one God is partitioned into divine compartments).  Christians do indeed experience the Father as a distinct expression of God’s transcendence, the Son as a distinct expression of God’s mediation, and the Holy Spirit as a distinct expression of God’s immanence.  And, this may appear to non-Christians as though God’s divine nature is apportioned into three separate expressions.

Are the Father, Son, and Holy Spirit all the same thing?
No!  Many non-Christians are confused by the doctrine of the Trinity, thinking that the Father, Son, and Holy Spirit are merely three separate names for one and the same thing.  Christians do indeed experience the Father as God, the Son as God, and the Holy Spirit as God; and this may appear to non-Christians as though the three are indistinguishable.

 So, why is the doctrine of the Trinity so important?
The doctrine of the Trinity is not a matter of intellectual curiosity or theological gymnastics.  As mysterious as it is, it is important to understand this doctrine because it confronts us with questions and answers which lie at the heart of our relationship with God.

Presbyterians believe that the doctrine of the Trinity is important for a number of reasons.  First of all, Presbyterians have always stressed that the will and action of Jesus (the Son) are the same as the will and action of God.  The doctrine of the Trinity re-emphasizes that, if Christ is for us, then God Himself is for us and not against us.

Second, the doctrine of the Trinity functions to insure that the Church is indeed the body of Christ—the continued work of Jesus Christ.  Presbyterians experience the indwelling of the Holy Spirit as the very life of God Himself.  We believe that the God Who was in Christ (the Son) is the same God Who lives in us.  The doctrine of the Trinity is a way of saying that God’s grace which Christ brought to the world is the same grace which we (the church) bring to the world by the power of the Holy Spirit.

Third, we Presbyterians can see this doctrine as a source of assurance that in our worship of Jesus Christ, we are worshiping God Himself.  It is a doctrine that gives us confidence that we are not worshiping a mere creation from God, but we are worshiping God our Creator.

Finally, we see the doctrine of the Trinity as part of the doctrine of the divinity of Jesus Christ: as God the Son, Jesus is not just the embodiment of a part of God, but was the full presence of God with us—“Emmanuel” (Matthew 1:23).