One of Many Unions

This post marks the beginning of a series of reflections prompted by reading Union with Christ: In Scripture, History, and Theology by Robert Letham,¹ in preparation for the BCUK 2026 conference on Union with Christ.

Where Does It All Begin?

When considering union with Christ, my instinct is to focus on the believer’s participation in Christ’s life, death, resurrection, and glorification, much like the definition found in the Lexham Survey of Theology:²

Through the agency of the Holy Spirit, Christians are united with Christ in his life, death, resurrection, and glorification.

However, such a definition forces us to start near the conclusion rather than the beginning of the story. Letham traces the foundation of our union with Christ back through a series of prior unions that run throughout Scripture. These earlier unions provide a necessary framework for understanding what it means for finite, created beings to be united with Christ, the eternal Son.

Letham observes:³

Indeed, the Christian faith can be summed up as, inter alia, a series of unions. There is the union of the three persons in the Trinity, the union of the Son of God with our human nature, the union of Christ with his church, the union established by the Holy Spirit with us as he indwells us. Each of these unions preserves the integrity of the constituent elements or members, being at once a real union and simultaneously not absorbing the one into the other.

This final sentence is crucial. Each of these is a real union: there is a permanent joining together, yet not a blending or confusion of the distinct elements involved. There is no dissolution of identity. This idea can help us begin to make sense of our own union with Christ. It also leads us to consider how the Church has historically reflected on these earlier unions, particularly the union of the Son of God with human nature, as a way of clarifying what our union with Christ is and what it is not.

Another key emphasis is the role of the Holy Spirit across these various unions. As a person of the Trinity, the Spirit is instrumental in creation, the incarnation⁴ and is later given to the Church at Pentecost. His presence is not merely functional, but constitutive. Each union is an act of divine initiative and power, which gives to it permanence and security.