Christians are united in saying that the Christian life is a life in the Spirit. But the unity breaks down when explaining how the Christian life is a life in the Spirit. Life in the Spirit is the first book to engage the post-Constantinian critique of the church with the field of Spirit Christology. Building upon the work of post-Constantinians John Howard Yoder and Stanley Hauerwas and upon the Trinitarian Spirit-Christology of Leopoldo Sánchez, this account provides a framework for seeing one’s Christian life as one transformed by the Spirit. Snavely rejects the characterisation of life in the Spirit as bringing sinners to faith, and instead proposes that as Jesus lived as the Son of the Father in the Spirit, the Spirit also makes other sons of the father in the image of Jesus. This Trinitarian interpretation shows the Christian life as being one of total trust in God with one’s own life, and after death living in Jesus’ resurrected life in the Spirit. Snavely’s account calls for a reimagining of the church and the Christian life in terms of ecclesial structure, Christian discipleship and the Christian view of marriage. Life in the Spirit will not only help Christians to have a better understanding of the place of vocation in the world as witnesses to the lordship of Jesus Christ, but it will also promote unity in the body of Christ based on the actual unity that all his adopted sons and daughters already have by belonging to Jesus Christ’s life in the Spirit.