It is census day on Sunday and, despite sterling efforts from many interested parties, angry controversy around this quaint operation has not quite been ignited. I particularly enjoyed the attempt to muster a boycott on the grounds that the UK subsidiary of Lockheed Martin, the world's largest arms company, had been contracted (again) to conduct the thing. Because that's what you want, isn't it? To make sure arms companies stay totally focused on their core business, and don't start piddling around in more peaceable activity?

I filled in my household's form with some alacrity, not least because the part of me that will always be a 10-year-old goody-goody schoolgirl simply loves the opportunity to print in lovely, neat, black capitals. It wasn't until after it had been mailed – why not? Keep postpersons employed – that I caught up with the British Humanist Association's plea: "We urge people who do not want to give continuing or even greater importance to unshared religions in our public life to tick 'No Religion' in the census."

Actually, I had ticked "No Religion". But I still don't like the tenor of this instruction. I don't want to stand against "believers". I am still, for my secular sins, a wet multiculturalist, minded to put up with the beliefs I can't share, whenever possible, in the interests of strengthening those that I can. I'm combative and dogmatic by nature, but I don't think these are among the finest of human qualities. I used to be a combative and dogmatic atheist. But then I realised that combat and dogma might be the problem.

Combat especially, of course. It is a popular atheist assertion, the one that says religion causes war. As if humans would never fight over land, or resources, or power, or out of sheer, carnivorous, animal aggression. Humans cause war. So do chimps and bonobos, our close genetic relatives. Perhaps Lockheed Martin is on a religious mission? Yeah, right.

I was in Motherwell, my home town, outside Glasgow, a few weeks back, on the evening that a recent Rangers v Celtic match descended into on- and off-pitch aggression the like of which had not been seen in 20 years. The Old Firm antipathy is characterised as "religious". But really it's tribal. No one goes home pissed and full of anger because the guys that scored the goals believe in transubstantiation. People go home pissed and full of anger because they left home with the intention of getting that way, and had signed up for it as toddlers. And that's not good.

The British Humanist Association is right to identify the segregation of state institutions as a powerful factor in augmenting the sort of antipathy that the Old Firm shelters. It cites a poll of 1,896 people, in which 61% identified with a religious denomination while only 29% said they were religious. The argument is that the statement of "empty" religious identity results in data that is used to justify continued religious privilege in state policy on public services. The real question is why people cling to a religious identity when they have no religious faith. It's the desire, surely, to be in one team, and opposed to another – a cultural need, a human need, even, a need that helped to deliver humans to the top of the food chain, for better, for worse, or for a bit of both.

Despite great effort to find them, human saints are hard to come by. Julian Assange, for example. Good guy? Bad guy? Perfect guy? Flawed guy? How about a mass of contradictions? That's where I really become uncomfortable with humanism. The British Humanist Association says: "Humanists are atheists and agnostics who make sense of the world using reason, experience and shared human values. We take responsibility for our actions and base our ethics on the goals of human welfare, happiness and fulfilment. We seek to make the best of the one life we have by creating meaning and purpose for ourselves, individually and together." Nothing much to complain about there (although a bad person might say words such as "smug" and "piety"). Well, unless you fail to subscribe to the idea that humans are essentially good and wise, rather in the manner that humans tend to characterise the gods they invent and worship.

Mostly, humanism sounds like religion without God, a kind of collective, earnest, well-meaning narcissism. People are welcome to it, if it floats their boat, though the proselytising does demand response, of course. The call to reason forgets that any atheist worth his salt understands that God does exist, but only in the minds of some of those humans who are not entirely and absolutely governed by reason. Which, I would say, is all of us. Few humans live their entire lives in reasonable refusal of all thoughts and deeds that are bad for them, or for others. People often turn to God as a means of helping them to find the discipline to avoid such behaviour. Humanists appear to believe that the opposite is the case. It's dogma – irreligious mumbo-jumbo really – and should not be confused with secularism.

For the fact is that there are plenty of reasons to be relaxed about the attractions of plain secularism, as opposed to humanism. A study, from Northwestern University and the University of Arizona, analysed census data from 85 countries, some of it stretching back a century, and presented it this week at the American Physical Society meeting in Dallas.

In nine countries, Australia, Austria, Canada, the Czech Republic, Finland, Ireland, the Netherlands, New Zealand and Switzerland, the analysis found that there has been a steady rise in the number of people claiming no religious affiliation. Religious belief, in all these countries, is fading slowly away, and organised protest against it does not appear to be the reason for this. Richard Wiener, who led the research, says: "put simply, it shows that social groups have a kind of 'gravity' that drags in more people the bigger they are". The tide of history is running against the religious. Conspiring to help that powerful tide risks provoking the entrenchment called fundamentalism.