When I announced I was writing a book on union with Christ, a friend messaged me and said, “I am too!” Two years later, not only have we both released books on the subject (Home with God: Our Union with Christ and One with My Lord), but more are coming out in the year ahead.

This isn’t a new doctrine. It’s deeply biblical, and it’s been showcased by every major theologian in the church’s history. Union with Christ isn’t a new idea; it’s an old idea being rediscovered.

Union with Christ is a believer’s identification with, incorporation into, and participation in all of Christ’s life. In Christ are all the blessings and benefits of salvation. To put it simply, union with Christ is our home with God. Though the doctrine exists throughout Scripture, it shines in the prepositions of the New Testament, especially in Paul’s letters, when he uses language like “in Christ,” “with Christ,” and “through Christ.”

In just the first three chapters of Ephesians, we get more than 30 mentions of union with Christ. Here are examples:

• God blessed us in Christ (1:3)
• God chose us in him (1:4)
• We’re predestined for adoption through Jesus Christ (1:5)
• We’re blessed in the Beloved (1:6)
• In him we have redemption through his blood (1:7)
• In the fullness of time, all things will be united in him (1:10)
• We’ve been made alive together with Christ (2:5)

Once you see union with Christ in the New Testament, it’s obvious through Scripture’s whole story. That’s good, because it addresses pressing questions about our identity, our belonging, and our purpose.

Identity: Who Am I?

In Christ, we see ourselves clearly.

We live in an age of identity confusion. But, contrary to what we might think, identity confusion isn’t fundamentally a cultural imposition. It’s a theological reality. Sin fractured our fellowship with God, with self, with one another, and with the created order. Subsequently, we’re born into this world not knowing who we are but with a desperate desire to become something.

In Christ are all the blessings and benefits of salvation.

Many seem to think the cure for this identity confusion will be of our devising. But we won’t solve the problem of a fractured identity by constructing it on our own. Babel shows us what happens when we try to build a great name for ourselves: We end up exhausted, confused, and scattered.

Union with Christ provides a sure and steady anchor for our identity. Who are we? In Christ, we’re the Father’s righteous and beloved children because we’re in the righteous and beloved Son. In Christ, our differences don’t have to be deified or denied. Instead, they’re dignified. In Christ, we can stop trying to life-hack our identity and receive a new one.

Belonging: Who Are We?

In Christ, we’re welcomed into God’s family.

People in the global West are growing more anxious, lonely, and discouraged. The spirit of expressive individualism is alive and well. Its harvest is rotten. Belonging to God’s family helps address our culture’s loneliness epidemic.

We were formed for fellowship, designed to live in communion with God and his people. The triune God created us out of the deliberate overflow of his own eternal delighting fellowship and love. Salvation is forgiveness and fellowship, acquittal and adoption, righteousness and relationship. In Christ, we aren’t just forgiven by the holy God—we’re welcomed to the table of the delighting Father. We’re God’s children and members of his family (the church) in Christ.

Christ doesn’t merely make each of us a new person; he welcomes us into a new people. Union with Christ is the bedrock not only of our doctrine of salvation but also of our doctrine of the church. When the church gathers in worship each week, our fellowship with one another is a reminder of the fellowship we have with God. As we worship, shoulder to shoulder, underneath it all is a whisper: “As close as I am to the man or woman beside me, Christ is nearer still.” In Christ, we receive a “new we.” And this new people is marked by a new way of living.

Purpose: How Do I Live?

In Christ, we’re invited to participate in God’s world in God’s way. Union with Christ is an invitation into real and ongoing participation in God’s story. In Christ, we “live and move and have our being” (Acts 17:28).

As we’re welcomed in Christ into communion with God, we’re free to obey God, knowing the review on our lives is already in. God isn’t going to change his mind about us. There isn’t a future version of us that God is going to love more. The apostle Paul asks, “What shall we say to these things? Are we to continue to sin that grace may abound? By no means!” (Rom. 6:1). He grounds his exhortation to the church in the assurance that “our old self was crucified with [Jesus] in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin” (v. 6). Union with Christ is the fertile soil for obedience, worship, and mission.

Having received this unbreakable, unshakable, and unchangeable union with Christ, all those in him are now free to pursue obedience to God’s better way in all things, knowing they can’t lose what God has declared is theirs forever in Christ Jesus. A “new way” is made ours in union with Christ.

Unique Union

This is the uniqueness of union with Christ: It’s a gift. What’s true of Christ by nature is given over to all who place their faith in him by grace. What we could never earn by way of grit, God gives over to us as a gift. We don’t even have to go searching for it. God invites us into it. In Christ Jesus, we’re invited to live at home with God.

We were formed for fellowship, designed to live in communion with God and his people.

We’re seeing renewed interest in the doctrine of union with Christ because it satisfies our deepest longings. We long to be given a beloved name, to belong to a whole people, and to have a clear sense of our purpose. The world around us is filled with such dissonance about these three questions that people, inside and outside the church, are looking for help. The world is longing for a home where the words “beloved,” “family,” and “meaning” are rooted in something more than cliché.

In Christ, the world—and we—can find everything we long for.