Although the doctrine of the Holy Spirit has often been a neglected subject in theology, it remains vital for understanding both the Christian confession of God as Trinity and the nature of the Christian life. In view of those two topics, God's Love through the Spirit examines the relationship between love and the person and work of the Holy Spirit in Thomas Aquinas and John Wesley two very different figures whose teachings on the Spirit and the Christian life are found to be, on the whole, surprisingly compatible. An investigation into Aquinas's amor-based pneumatology, including a ground-breaking analysis of his recently discovered Pentecost sermon, and a fresh assessment of the doctrine of sanctification in Wesley show that in distinctive yet largely complementary ways, Aquinas and Wesley provide resources that can be used to reclaim a richer pneumatology, specifically in relation to the theological virtue of love.

Despite the obvious differences between these two figures in method and style, there are certain conceptual parallels in their writings such as the central themes of love and holiness that create the possibility for mutual enrichment among their respective theological heirs. Aquinas's pneumatology can be illuminated and amplified by the emphasis on the Holy Spirit and sanctification that is found in Wesley, even as the insights of Aquinas can aid Methodists and Wesleyans in accounting more fully for the properly theological, and indeed Trinitarian, basis of sanctification. The conclusions reached in God's Love through the Spirit, particularly concerning an understanding of love both within God's own life and in Christian participation in God by grace, challenge the claim that Western theology suffers from a pneumatological deficiency, and represent a significant contribution to the study of Aquinas and of Wesley, to ecumenical dialogue between Catholics and Methodists (and Protestants more broadly), and to the retrieval and development of a genuinely constructive pneumatology.