This excellent book has many facets, but there is an overarching theme: the tension between the necessity that a religion claims to speak a universal truth (‘without the conception of an objective reality as a goal or target, we are treading the short path to nihilism’; p 41) and the moral imperative of tolerance in a world of different and contradictory faiths. Succeeding chapters discuss the problems of both ideas. Regarding the first, Trigg has much to say about the proposition that the existence of different and contradictory religions may suggest that none of them is true. I am not sure about the logic of this: the fact that contradictory religions cannot all be true is surely neutral as to whether any one of them is. The variety of religions perhaps suggests something else: namely that, if there is an omnipotent God, that God has made it singularly difficult for humankind to accept God. Trigg cites the atheist Bertrand Russell's answer to the question of what would he say if he found himself before the throne of God after his death: ‘Why didn't you give more evidence of your existence?’ (p 82).

Chapters 2 and 3, and in particular the critique of Professor John Hick's attempt (influential – see pp 56 ff – but surely hopeless) to reconcile religious objectivity (‘the Real’) with the idea that ‘all religions (or, at least, many) [are] equally valid’, amount to a mind-clearing exercise of great value. It is, I think, a melancholy fact that the desire for such reconciliation as Hick advocates is both noble and doomed. Its nobility is demonstrated by the plea of Aurelius Symmachus, Prefect of Rome, in 382 ad to Emperor Valentinian II for the restoration of the Altar of Victory to the Senate House in Rome:

This is a noble claim to a kind of spiritual brotherhood. Valentinian, however, refused the petition at the insistence of Ambrose, Bishop of Milan.

That Hick's enterprise is doomed is amply demonstrated by Trigg. Hick's view appears driven by his desire ‘to legitimize different religions in the eyes of each other … his own critical realism appears to leave us without the ability to say anything with assurance about what ultimate reality is really like’ (p 54). Thus to effect his false reconciliation Hick has to deny the Real any description; but that makes it nothing. Symmachus’ noble plea is flawed for the same reason.

The second theme, tolerance, is to my mind much less straightforward. The question of how in a civilised state we are to deal with religious diversity is not simply answerable by an appeal to logic but requires the questioner to enter into the messy world of judgement: whether this or that is the better policy. Trigg cites the instance of Catholic adoption societies in England that refused to place children with same-sex couples (p 146). Unsupported by public funds, as I understand it they ceased to operate. ‘This poses a general conundrum about religion and diversity … Can divergences from norms be tolerated?’ (p 147). Trigg has no clarion call for an answer, nor should he; the only answer is ‘sometimes’: sometimes the freedom to differ from the norm needs to be upheld, sometimes not. The balance to be struck between freedom and conformity is not static. It is by no means surprising, therefore, that Trigg's voice is less certain on tolerance than it is on truth. As he says: ‘The problem is where to draw the line and decide what can and what cannot be tolerated’ (p 172).

The chapters on education (Chapter 6) and freedom (Chapter 10) are particularly valuable. At the very end of the book Trigg says: ‘Freedom, reason, and the idea of truth are all indissolubly linked. Remove one and all else fails’ (p 187). I think that this is an important – basic – reality, though it does not tell us quite how all these pillars may be made to hold up the same roof. Some of Trigg's reflections on the overall theme of tolerance are less clearly right. There are a number of references to democracy, for instance:

I doubt this second sentence. If democracy is a form of government based on the supremacy of the people's will, then we have to recognise that the legally enforced recognition of minority rights, sometimes unsavoury and often unpopular, is essentially undemocratic; the people's will, on the whole, may well be against them. To protect individual liberty we need constitutional mechanisms which are not necessarily vouchsafed by the popular will. Democratic rule is a necessary, but not a sufficient, condition of a free society.

This is something of a distraction, for Trigg is not, of course, writing a treatise on the forms of political government. But it serves to underline the difficulties in finding a political, even a constitutional, answer to ‘The problem … where to draw the line and decide what can and what cannot be tolerated’.

This is an important book on a difficult subject. It is not easily digestible, for it is crowded with ideas which tumble across the page. But gathering them together is well worth the effort.