With reference to the impact of Mediaeval Christianity, Booker looks at the narratives of Beowulf, the legend of King Arthur, and (from late mediaeval) Dante's Divine Comedy. He writes:
Immeasurably remote though it now seems to us, the world-picture developed by mediaeval Christendom was one of the most remarkable achievements of the human imagination. For the peoples of Christian Europe it provided a psychological framework which could explain and give meaning to the entire way in which they viewed their existence...In contrast, concerning the impact of the Reformation, Booker writes:
So all-embracing was this 'Christian myth' that it could give a sense of significance to every aspect of individual and collective life. And not the least reflection of its power was the way ... the chief visual self-expression of European civilisation, alongside its churches and cathedrals, was centred on a particular set of images, endlessly painted, sculpted and depicted in stained-glass, the purpose of which was constantly to focus people's minds on this other dimension to their lives. These stylised icons of the crucified Christ and the Mother and Child made no attempt to relate to the imperfect, everyday, material world. They were windows onto that eternal plane of perfection which was regarded as the only true reality.
"The Seven Basic Plots", Christopher Booker, p.633
Like Luther when he declared 'here I stand, I can say no other', [sic] they had found a new source of authority in their own judgement, as they looked anew at the image of Jesus presented in the Bible, the book on which Christianity rested. Possessed by this new vision of the Self, they set about destroying all those outward trappings which had been designed to convey religion as the gateway to an other-worldly spiritual dimension. In their newfound zeal, they tore down statues of the saints and images of the Virgin, poured contempt on the belief in Purgatory, and lectured bemused worshippers that unless they were among the 'elect', chosen by God, they faced eternal damnation. But as they did so they became all to easily inflated by that self-righteousness which arises from confusing ego with Self, potentially the most deadly form of egotism of all.His perspective is therefore (I think) that mediaeval Christianity, with its mythologising of Christ and moving him and the narrative surrounding him into an idealised world, represented a high point of Christian coherence. In contrast, whilst the Reformation might have returned people to the Scriptures, the consequence was the loss of a coherent worldview, and a movement of people away from the idealised, integrated perspective on the world that they had in the mediaeval era.
I would largely disagree with this analysis. Whilst the mythological perspective may have expressed a coherent worldview, it was also one which largely served the interests of a small but privileged group - the people at the top of the feudal system and the powerful church. For most people living in the mediaeval era, the structure of christendom rationalised their miserable existence of squalor, high taxes, poverty, disease and hunger whilst holding out a vague carrot if they were good of a much better place after they died.
On the other hand, the Reformation worldview helped with the move away from the feudal hierarchy, and pointed towards the accountability, checks and balances that we take for granted in the modern world. People no longer had special status because they happened to have been born into the right family: all humans had dignity before God. This is something that is very apparent in Reformation art. No longer are religious characters painted in a kind of idealised way, disconnected with the real world. They are painted in a proper relationship with the world around them. Also, real people are portrayed as proper subjects for painting - it isn't simply the "perfect" world that has value, but the real, everyday world. In reflecting this, it is also consistent with Christianity as it is found in the Bible, where God is sufficiently concerned for humanity that he takes on humanity, in the person of Jesus Christ. Christianity is not a mythological idealisation; it is the story of how God directly intervened in human history through the incarnation.
Also, whilst the mediaeval worldview may have had some coherence, it was fundamentally a matter of human tradition. The Reformation worldview had - and indeed still has - as its foundation the Bible. In principle, people are invited to search the Scriptures (as the Bereans did in the Bible itself!) to see whether what is being said by Christian teachers actually corresponds to what the Bible says - the teachers themselves only have authority insofar as they reflect the Bible's authority. The mediaeval worldview may have been derived from the Bible at one stage, but the traditions of the church, designed to serve its own interests rather than be faithful to the Bible, added to the integration of Aristotleian thoughtforms, meant that this worldview was a product of human imagination and tradition rather than one which reflected the Bible. And if one worldview reflecting human imagination and tradition can be considered authoritative, on what basis can any other such worldview be rejected?
Of course, this sounds like a good modern "tolerant" approach - but don't forget that it was in the context of mediaeval Christianity that it was considered reasonable for the Christian worldview to be forcibly imposed on the rest of the world through the Crusades and the work of the Inquisition. Whilst the Reformation worldview may appear less tolerant, more absolute, the proper understanding of Reformation principles of the dignity of all humans have meant that Christians have not considered it appropriate to use military strength to enforce their beliefs on the rest of the world.
It is also the case that, in conjunction with the Renaissance, the Reformation was unconsciously a step towards the Enlightenment, and humans becoming "autonomous" - believing themselves to be independent from any sort of external absolute. This was not an inevitable consequence of the Reformation - had the focus remained on the Reformation solas - Scripture, Christ, faith, grace - European civilisation might have been saved from the negative consequences of rationalism that followed in subsequent centuries.