Harald Lindstrom's classic study of John Wesley's doctrine of sanctification remains the most accurate and comprehensive description we have of the theology of the founder of Methodism. Its accuracy stems from the fact that Lindstrom relied principally on Wesley's sermons to define his understanding of scriptural Christianity. Its comprehensiveness reflects the fact that John Wesley saw, and spent his lifetime explaining, that the promise of salvation was the central theme of biblical theology and that the experience of sanctifying grace was the essence of salvation.