“Filioque?” The Controversy between East and West over the Procession of the Holy Spirit, by Professor Remus Runcan, is an impressive study that treats an important subject in Christian theology which has received little attention in Romanian evangelical theological writing.The author analyses the historical and biblical-theological background to the expression filioque with the purpose of formulating a possible line of approach towards the reconciliation of the two theological positions, as developed over the course of Christian history by the Orthodox and Roman Catholic churches, that have been adopted in relation to this issue.In the first part of the study the author discusses the clause about the Holy Spirit in the Niceno-Constantinopolitan Creed in order to better understand the context of the theological controversy. In the second part he analyses the main relevant biblical texts and Patristic writings, together with the views of major theologians from the Orthodox, Catholic and Protestant traditions, in an endeavour to grasp the relations between the Son and the Holy Spirit within the Holy Trinity. He also discusses the way the filioque clause influences other vital Christian doctrines, including those of the Trinity, Christology and Ecclesiology. In the final part of the work he explores the possibility of a reconciliation between the two traditional positions with regard to the filioque clause and advances a number of practical ways forward.In this work Dr Runcan succeeds in highlighting the way in which a single word – filioque – has impacted a number of Christian doctrines over the course of time, thus bringing about a shifting of the centre of gravity in Christian theology away from spirituality and towards history. Dr Runcan’s book represents a valuable resource not only for those interested in the study of theology but also for any church member who is concerned to strengthen their faith.