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 groundbreaking 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.