There are as many atheisms as there are gods. We spend most of our lives disbelieving in things without wasting time asking why, and quite right too. So what is it that makes some particular forms of disbelief intellectually fertile or socially significant? Nick Spencer’s short history of atheism goes a long way towards answering this question, and anyone seriously interested in religion and irreligion today should read it.

The first shock of the book is just how old the strongest atheist arguments are. Spencer doesn’t quote my favourite, a Babylonian tablet from around 1,000 BC that was referenced in Robert Bellah’s book, but the Book of Job is certainly a powerful argument against what you might call the corporate PR department of GodCo.

Over in Greece, the logical difficulties of an omnipotent and benevolent God were clear as soon as people got the concepts of omnipotence and benevolence straight. Everything you needed to be an intellectually fulfilled disbeliever in the Christian God was in place by the birth of Christ.

In this light, it’s remarkable not that there are atheists today, but that there were so few in the long centuries of Christendom’s glory. I don’t think persecution or the fear of persecution can account for this. It did not manage to suppress all manners of subtle heresy; why should it successfully suppress the most obvious and radical objection to the whole business?

One answer, Spencer suggests, is that important atheism is always secondary to theism. For any particular atheism to matter, there must be an important conception of God to be rejected; in that sense, atheism is closely related to blasphemy. And the concept of God is itself extremely flexible: some are so strange as to be unrecognisable as gods to other worshippers, which is one reason why the early Christians themselves appeared as atheists to the pagans around them.

Arguments against God’s justice, such as those we see in Babylon, are not arguments against his existence: they are arguments about his character, which presuppose that he has one. Modern atheism, in the sense of a rejection of Christian monotheistic conceptions of God, doesn’t really get started until the 18th century. But by the French Revolution, modern western arguments were clear except for the faith in science, which emerged in the next 100 years.

The study of how these arguments spread and ramified into their modern forms turns out to be historical and political, rather than philosophical. It was impossible to separate a reaction against Christianity from a reaction against the Christian church, and so the forms this opposition took was determined by the role of the church in the societies involved.

In France, Italy and Russia, autocratic and clerical regimes bred a fierce anti-clericalism, which slaughtered thousands of priests and nuns and tens of thousands of believers whenever a revolution brought it to power. In Germany and countries in the German cultural sphere, atheism was far more of an intellectual matter and the Protestant churches went much further towards meeting atheist arguments in good faith.

In Britain, Spencer argues, the weight of the Anglican establishment would have been a much more powerful stimulus to atheism had it not been for the presence of thriving traditions of leftwing Christianity – this was not just Methodism and the socially conscious forms of Anglican belief: the Catholic church in this country was on the side of the working classes against most of the establishment in a way unthinkable elsewhere in Europe. Of course, that had more to do with the situation of Ireland than with theology.

So the atheisms of modern England shadow those of Anglican England, ranging from a mild an undogmatic benevolence to rebarbative sectarian fervour.