Mention of Opus Dei will raise eye-brows in some quarters when considering this book. However the author’s exposition of the movements aims is engaging and it soon becomes apparent that the central theological theme behind it – here termed ‘divine filiation’ – is of vital importance to all Christians; Catholics, members of Opus Dei, or not. Divine filiation related to divinization and deification seen as the central goal of the Christian life, and ultimately the very being of the soul in relation to God, has been, if not quite lost in some circles, then at least grossly under played. Hahn’s book is a contribution to the necessary re-balancing.