I have to sympathise with someone who doesn't want to drive an atheist bus, like the Christian bus driver who made the news today. I have enough trouble driving a car without hitting stationary objects, so the thought of driving any kind of bus makes my palms sweat. If I had to do it, I would definitely want God on my side, preferably willing to take the wheel in an emergency. Posters on the bus likely to put him in a bad mood would be a terrible idea.

Ron Heather's objection, however, is a principled one, concerned more with religious offence than road safety. He turns up for work, sees that he's expected to drive around in a big red denial of the existence of God, and refuses.

We all have things that we find offensive, and wouldn't want to be confronted with them in the course of our daily work. I'd hate to come downstairs of a morning to find Jeremy Clarkson's face stuck all over my laptop.

But the atheist bus poster still seems an odd thing to make such a fuss about. For a start it doesn't say anything nasty about God, just that he probably doesn't exist. Many people have said much ruder things about him, and he always seems to take it pretty well.

It also happens to be a statement of the basic religious beliefs of a lot of British people. Considering the number of religious groups who advertise on public transport, if all drivers took Heather's stance, the result would be pretty chaotic. No Christians, Muslims or other believers could drive an atheist bus. And if a bus had a poster with a verse form the Bible about Jesus dying for our sins, no atheist or Muslim could drive it. If it advertised the Qu'ran – you get the picture.

And what would happen with a bus that had an ad for the Qu'ran on the inside and for Jesus on the back? It could only be driven by someone who believes all religions lead to God.

In fact, "There's probably no God" is more a statement of agnosticism than atheism, so a really principled hardline atheist ought to refuse to drive the so-called atheist bus too.

Most of us, I think it's fair to say, don't want a religiously segregated public transport system. Perhaps there's enough room on the buses for all religions to have their say without anyone walking out.

In fact, speaking as one myself, I think it shows quite a cheek for Christians to make a fuss about this. We've spent decades covering public places with verses from the Bible, and posters promising that if you let Jesus into your life everything will be all right for ever.

Then as soon as the opposition get the money together to do the same thing we're outraged, and think that God is as cross as we are.

Personally, I think that if God is anything like as big and clever as we claim he is, he can probably take it.