This work deals principally with the history of Christianity in Europe, with particular reference to Spain, tracing the movement of the original Unitarian followers of Jesus (Isa (AS)), from North Africa and the Middle East up into Europe and Spain. It goes on to describe the formation and expansion of the Trinitarian Church in Italy and the rest of Europe and outlines the almost total annihilation of the Unitarian Christians at the hands of the Trinitarian Church by means of the Mediaeval Inquisition. This is useful in understanding how Islam was able to spread so readily and rapidly in Andalus.