In my role as Director of Academic Growth and Formation at Asbury Theological Seminary, I’ve had the privilege of teaching both church history and basic Christian doctrine for the past few years. I enjoy teaching both courses, as they complement each other in outlining and reinforcing the development of the doctrine of the Trinity in the early church. I’m particularly grateful for the opportunity this work has given me to return to the foundational doctrines of the Christian faith. At the very center of these doctrines is the doctrine of the Trinity, essential to understanding key passages of Scripture like Romans 8:16-17.

The third doctrine of The Salvation Army states: “We believe that there are three persons in the Godhead—the Father, the Son and the Holy Ghost, undivided in essence and co-equal in power and glory.” 

This is a beautiful articulation of one of the central teachings of the Christian faith. The doctrine of the Trinity is foundational to Christianity, but why is it so central? 

Because the doctrine of the Trinity tells us who God is.

Christians have sometimes shied away from teaching and preaching the doctrine of the Trinity because it can be easily misunderstood and involves an element of mystery. Many well-meaning attempts to explain how three persons can be undivided in essence often lead to errors, either by emphasizing unity at the expense of differentiation, or by focusing too much on differentiation while neglecting unity. 

For example, a common but flawed analogy for the Trinity is the common comparison to H2O, which can exist in three forms: solid (ice), liquid (water) and gas (steam). While all of these forms are in fact H2O, this analogy reflects the heresy of modalism, which suggests that God appears in different “modes” in salvation history but is really just one being changing appearances (much like Clark Kent becoming Superman).

Augustine, one of the Fathers of the early church, used another analogy to describe the Trinity:  the relationship between the one who loves (the Father), the one who is loved (the Son), and love itself (the Holy Spirit). One of the things I appreciate about this image is its emphasis on relationship and connection within the life of God. 

Consider Genesis 1:26-27: “Then God said, ‘Let us make mankind in our image, in our likeness, so that they may rule over the fish in the sea and the birds in the sky, over the livestock and all the wild animals, and over all the creatures that move along the ground.’ So God created mankind in his own image, in the image of God he created them; male and female he created them” (NIV).

Scripture teaches that humans are created in the image of God. One way of thinking about the Trinity, along the lines of Augustine’s description, is that God is in God’s own life community. There is an eternal oneness, a perfect unity, between the Father, Son and Holy Spirit. 

This means that humans, created in God’s image, are made for community and connection. We are made for relationship. I often say that it’s not a matter of whether you will connect with something or someone, but rather a matter of what you will connect with.

The doctrine of the Trinity is significant because it compels us to think about our need to connect with the Triune God who created us. It also reminds us of our deep need for meaningful places of belonging and connection.

The Salvation Army recognizes this need in its own mission. Many people, especially those struggling with addiction, find profound connection with others on a similar journey when they enter the structured environment of an Adult Rehabilitation Center (ARC). I believe ARCs are one of the most powerful tools the Lord has placed in the Army’s hands to fight the enemy and claim territory for the Lord Jesus Christ.

The Army’s roots lie in the revival fires of the Methodist movement. This is the branch of the Christian family tree where The Salvation Army is grafted into the larger Body of Christ. John Wesley, the founder of Methodism, would have appreciated the disciplined way the Army structures its life together.

Wesley himself structured the life of Methodism with great care, but the purpose of this structure was not merely organizational. It had a two-fold aim. 

First, Wesley wanted to ensure that everyone in the Methodist movement would be deeply connected to the Triune God. He wanted people to know God’s love, through the person and work of Jesus Christ, and the empowering presence of the Holy Spirit. Wesley was passionate that people not only hear the gospel, but that they receive deep assurance that they are beloved by God the Father. Wesley loved to preach on Romans 8:16: “The Spirit himself testifies with our spirit that we are God’s children” (NIV). Through the Holy Spirit, we can have a profound certainty that we are God’s children. Praise God!

Romans 8:17 completes the trinitarian logic of this beautiful passage: “Now if we are children, then we are heirs—heirs of God and co-heirs with Christ, if indeed we share in his sufferings in order that we may also share in his glory” (NIV).

Do you see how essential the Trinity is to this passage and its promises?

God the Father wants to adopt us into sonship. Through the work of Jesus Christ, the way is opened for us to become children of God. Through our adoption into God’s family, we become “heirs of God and co-heirs with Christ.” And the Holy Spirit testifies to us that this has happened, so we no longer live in fear or uncertainty about our connection to the Lord. 

This is why the gospel is such good news!

Have you received this good news? Has it reoriented your life? What would it look like for you to more fully embrace the promises of Romans 8:16-17?

Has the Spirit testified to your spirit that you are a child of God, an heir of salvation and the kingdom of God? If not, ask and you will receive. Seek and you will find. Knock and the door will be opened (Matthew 7:7).

If you have received this promise, your work may be to wrestle with the reality that the servant is not greater than the master. We receive what Jesus, the Son of God, receives. But we are also called to walk the same road of full submission and surrender that our Lord walked. Are you willing to share in the sufferings of Christ to share in His glory?

Let the doctrine of the Trinity draw you deeper into communion with the one true God!

This article was originally titled “The Trinity: More Than a Doctrine, a Divine Invitation” in the March 2025 issue of The War Cry. | Illustration by Matt Chinworth