Too many atheists miss the point of religion, it's about how we live and not what we believe, writes John Gray.

When he recounts the story of his conversion to Catholicism in his autobiography A Sort of Life, Graham Greene writes that he went for instruction to Father Trollope, a very tall and very fat man who had once been an actor in the West End.

Trollope was a convert who became a priest and led a highly ascetic life, and Greene didn't warm to him very much, at least to begin with.

Yet the writer came to feel that in dealing with his instructor he was faced with "the challenge of an inexplicable goodness". It was this impression - rather than any of the arguments the devout Father presented to the writer for the existence of God - that eventually led to Greene's conversion.

The arguments that were patiently rehearsed by Father Trollope faded from his memory, and Greene had no interest in retrieving them. "I cannot be bothered to remember," he writes. "I accept."

It's clear that what Greene accepted wasn't what he called "those unconvincing philosophical arguments". But what was it that he had accepted?

We tend to assume that religion is a question of what we believe or don't believe. It's an assumption with a long history in western philosophy, which has been reinforced in recent years by the dull debate on atheism.

In this view belonging to a religion involves accepting a set of beliefs, which are held before the mind and assessed in terms of the evidence that exists for and against them. Religion is then not fundamentally different from science, both seem like attempts to frame true beliefs about the world. That way of thinking tends to see science and religion as rivals, and it then becomes tempting to conclude that there's no longer any need for religion.

This was the view presented by the Victorian anthropologist JG Frazer in his book The Golden Bough, a study of the myths of primitive peoples that is still in print. According to Frazer, human thought advances through a series of stages that culminate in science. Starting with magic and religion, which view the world simply as an extension of the human mind, we eventually reach the age of science in which we view the world as being ruled by universal laws.

Frazer's account has been immensely influential. It lies behind the confident assertions of the new atheists, and for many people it's just commonsense. My own view is closer to that of the philosopher Wittgenstein, who commented that Frazer was much more savage than the savages he studied.

I don't belong to any religion, but the idea that religion is a relic of primitive thinking strikes me as itself incredibly primitive.

Image caption Science helps us understand how the world works - but to what extent?

In most religions - polytheism, Hinduism and Buddhism, Daoism and Shinto, many strands of Judaism and some Christian and Muslim traditions - belief has never been particularly important. Practice - ritual, meditation, a way of life - is what counts. What practitioners believe is secondary, if it matters at all.

The idea that religions are essentially creeds, lists of propositions that you have to accept, doesn't come from religion. It's an inheritance from Greek philosophy, which shaped much of Western Christianity and led to practitioners trying to defend their way of life as an expression of what they believe.

This is where Frazer and the new atheists today come in. When they attack religion they are assuming that religion is what this Western tradition says it is - a body of beliefs that needs to be given a rational justification.

Obviously, there are areas of life where having good reasons for what we believe is very important. Courts of law and medicine are evidence-based practices, which need rigorous procedures to establish the facts. The decisions of governments rest on claims about how their policies will work, and it would be useful if these claims were regularly scrutinised - though you'd be well advised not to hold your breath.

But many areas of life aren't like this. Art and poetry aren't about establishing facts. Even science isn't the attempt to frame true beliefs that it's commonly supposed to be. Scientific inquiry is the best method we have for finding out how the world works, and we know a lot more today than we did in the past. That doesn't mean we have to believe the latest scientific consensus. If we know anything, it's that our current theories will turn out to be riddled with errors. Yet we go on using them until we can come up with something better.

Science isn't actually about belief - any more than religion is about belief. If science produces theories that we can use without believing them, religion is a repository of myth.

However rapidly our knowledge increases, we'll always be surrounded by the unknowable

Myths aren't relics of childish thinking that humanity leaves behind as it marches towards a more grown-up view of things. They're stories that tell us something about ourselves that can't be captured in scientific theories.

Just as you don't have to believe that a scientific theory is true in order to use it, you don't have to believe a story for it to give meaning to your life.

Myths can't be verified or falsified in the way theories can be. But they can be more or less truthful to human experience, and I've no doubt that some of the ancient myths we inherit from religion are far more truthful than the stories the modern world tells about itself.

The idea that science can enable us to live without myths is one of these silly modern stories. There's nothing in science that says the world can be finally understood by the human mind.

If Darwin's theory of evolution is even roughly right, humans aren't built to understand how the universe works. The human brain evolved under the pressures of the struggle for life.

Through science humans can lift themselves beyond the view of things that's forced on them by day-to-day existence. They can't overcome the fact that they remain animals, with minds that aren't equipped to see into the nature of things.

Darwin's theory is unlikely to be the final truth. It may be just a rough account of how life has developed in our part of the cosmos. Even so, the clear implication of the theory of evolution is that human knowledge is by its nature limited.

It's been said that the universe is a queerer place than we can possibly imagine, and I'm sure that's right. However rapidly our knowledge increases, we'll always be surrounded by the unknowable.

Image caption Rational argument did not lead Graham Greene to Catholicism

Science hasn't enabled us to dispense with myths. Instead it has become a vehicle for myths - chief among them, the myth of salvation through science. Many of the people who scoff at religion are sublimely confident that, by using science, humanity can march onwards to a better world.

But "humanity" isn't marching anywhere. Humanity doesn't exist, there are only human beings, each of them ruled by passions and illusions that conflict with one another and within themselves.

Science has given us many vital benefits, so many that they would be hard to sum up. But it can't save the human species from itself.

Because it's a human invention, science - just like religion - will always be used for all kinds of purposes, good and bad. Unbelievers in religion who think science can save the world are possessed by a fantasy that's far more childish than any myth. The idea that humans will rise from the dead may be incredible, but no more so than the notion that "humanity" can use science to remake the world.

No doubt there will be some who are deeply shocked by Graham Greene's nonchalance about the arguments that led him to convert to Catholicism. How could he go on practising a religion when he couldn't even remember his reasons for joining it?

The answer is that he did remember - but his reasons had nothing to do with arguments.

Human beings don't live by argumentation, and it's only religious fundamentalists and ignorant rationalists who think the myths we live by are literal truths.

Evangelical atheists who want to convert the world to unbelief are copying religion at its dogmatic worst. They think human life would be vastly improved if only everyone believed as they do, when a little history shows that trying to get everyone to believe the same thing is a recipe for unending conflict.

We'd all be better off if we stopped believing in belief. Not everyone needs a religion. But if you do, you shouldn't be bothered about finding arguments for joining or practising one. Just go into the church, synagogue, mosque or temple and take it from there.

What we believe doesn't in the end matter very much. What matters is how we live.