At the end of his General Theory of Employment, Interest and Money John Maynard Keynes (1954: 383) wrote ‘Practical men who believe themselves to be quite exempt from any intellectual influences, are usually the slaves of some defunct economist. Madmen in authority, who hear voices in the air, are distilling their frenzy from some academic scribbler of a few years back.’

Keynes is recognising the role ideas play in culture. Since the end of the 19th century this has taken the form of a discussion about ideology. Karl Marx in particular wanted to insist on the dialectic between ideas and modes of production. In the German Ideology he noted that morality, religion, and so forth,

In the third of his theses on Feuerbach Marx puts this more dialectically, reminding materialists inclined to read off the human condition simply from circumstances and upbringing that it is ‘human beings who change circumstances’ (Marx and Engels, 1976: 3). Just to spell this out: theologies, like all other forms of discourse, change as modes of production and material intercourse change, but equally human beings, believing thus and thus, celebrating the eucharist thus and not otherwise, change circumstances.

As an example of how religious ideologies bear on human circumstances E.P. Thompson (1968) (following Marx) cited Andrew Ure's Philosophy of Manufactures (1835/1967), to show how Christianity was used in industrial capitalism. Ure argues that religion is necessary to create a well-disciplined work force. Some power is needed to turn recalcitrant workers into docile wage slaves:

While it would be an overstatement to say that there are as many liberation theologies as there are practitioners, it is certainly true that liberation theology is not all of a piece. This is not just to point to the varieties of liberation theology – black, Asian, African, Jewish, feminist, womanist and so forth – but to the variety of standpoints even within Latin America, where the movement started. Juan Luis Segundo, for example, had an essentially evolutionary understanding of reality that he shared with his fellow Jesuit, Teilhard de Chardin. He can cite with approval the view that every vice was probably at some time a virtue, and that what we call ‘human beings’ are only slowly emerging from the tangle of primitive drives and instincts. He frankly avows a situation ethic, an ethic in which the ends justify the means, but on the understanding that Christian ends are the most communitarian and generous-hearted imaginable. José Míguez Bonino, on the other hand, offers us a survey of twentieth-century social ethics, but allows himself to formulate a principle that is virtually identical with utilitarianism: ‘The basic ethical criterion is the maximizing of universal human possibilities and the minimizing of human costs.’ Any economist would recognise this as a version of Pareto optimality. Enrique Dussel, for his part, who represents an appropriation of the work of Levinas long before that thinker became fashionable in Europe, describes ethics as ‘fundamental theology’, that which constitutes both the rationality and the possibility of theology.

Whilst it would be an overstatement to say that there are as many liberation theologies as there are practitioners, it is certainly true that liberation theology is not all of a piece. This is not just to point to the varieties of liberation theology - black, Asian, African, Jewish, feminist, womanist and so forth (and since feminist ethics are treated elsewhere in this volume, I will not deal with the subject here) - but to the variety of standpoints even within Latin America, where the movement started. Juan Luis Segundo, for example, had an essentially evolutionary understanding of reality which he shared with his fellow-Jesuit Teilhard de Chardin. He can cite with approval the view that every vice was probably at some time a virtue, and that what we call 'human beings' are only slowly emerging from the tangle of primitive drives and instincts. He frankly avows a situation ethic, an ethic in which the ends justify the means, but on the understanding that Christian ends are the most communitarian and generous-hearted imaginable. Míguez Bonino, on the other hand, offers us a survey of twentieth-century social ethics, but allows himself to formulate a principle which is virtually identical with utilitarianism: 'The basic ethical criterion is the maximising of universal human possibilities and the minimizing of human costs.'

It is often suggested that 'political readings' of Scripture are a recent invention, more especially of Marxist or leftist thought. That Scripture did not bear on human life together, on the 'polis', would however have sounded very strange to most Christians before the end of the eighteenth century, as a moment's reflection on the political involvement of the Byzantine and medieval Church will show. Martin Luther's two-kingdom doctrine, which taught that the Church and the state occupied two quite different spheres of responsibility, and which was very much a response to his own political situation, paved the way for the privatization of religion, especially in pietism. Luther himself, however, did not hesitate to draw the most brutal political consequences from Scripture. Where sixteenth- and seventeenth-century Protestantism read the whole Bible as the word of God, pietism focused on the New Testament, and the soul's relation to Jesus. The political context of the Old Testament was thereby lost to view. By 1790, in his Reflections on the Revolution in France, Edmund Burke is telling us that politics and the pulpit 'have little agreement', a foretaste of countless angry protests when church leaders have criticized political policies.