Professor Gregor Smith has done us all a service by writing an important, interesting and honest book. If I want to disagree with him, it is because he has made clearer to me than before what the issues are between secular Christianity and that kind of Christianity – which I shall call radical or revolutionary – which I think is the only alternative. We now know more precisely why there will soon have to be a frank showdown between two quite different kinds of leftwing Christianity. Pace Christopher Driver, we are not ‘all brother radicals under the skin’ (The Guardian, January 13th 1966) and my main debt to Professor Gregor Smith, and the point at which I part company with him most decisively, is that he shows me why his position is not nearly radical enough. Or perhaps it would be better to say he is radical only in a direction which is irrelevant to the real issues of our time, and offers a way of letting off steam through a kind of intellectual safety-valve which, like all safety-valves, works in fact to the preservation of the equilibrium of the present state of things. The trouble with his kind of ‘secular’ Christianity is that, like philosophers, ‘secular’ Christians have only ‘interpreted the world in different ways; the point is to change it’ (Marx, eleventh thesis on Feuerbach). Despite his protests to the contrary, Professor Gregor Smith is, in this respect, a philosopher, and his secular Christianity is, as I hope to show, a philosophical scheme rather than a living faith.