On a cold and dreary afternoon, I headed off to a destination I'd long avoided, to a farm that has been converted into a zoo. This zoo had got into trouble in the past because of links with the Great British Circus, which had led to its expulsion from an industry body, the British and Irish Association of Zoos and Aquariums, in 2009.

But there was something else about this place that I found unsettling: Noah's Ark Zoo Farm is a creationist zoo. You should perhaps expect that from its name. But biblical words and phrases are part of our cultural heritage, and don't usually imply biblical literalism (at least, I don't think the directors of the Eden Project have any religious agenda to push). I had browsed Noah's Ark's website, so I knew that the name was more than hinting at a religious flavour to this North Somerset attraction.

I walked in with some trepidation, expecting to be inundated immediately with religious propaganda. But there's little evidence of the creationist theme until you enter the large barn in the middle of the complex, which houses an auditorium and an impressive indoor children's play area. This, it seems, was the holy of holies. The walls were covered in posters, and they made for interesting reading.

"All in all, bacteria do not look as if they were the products of chance. They look as if they have been designed… Why has science closed its mind to the possibility that life was created?" asked one.

Another one presented "30 reasons why apes are not related to man". I prefer "humans" to the outdated, sexist "man", but let's move on. Come on! Humans are apes. Some of the "reasons" were just things that mark us out as a species, without implying that we're anything other than a hominoid at a broader level of classification. But there were also glaring inaccuracies. For example: "For apes… sex is functional… for reproduction." These people have clearly never watched bonobos for any length of time.

'There’s a Lego set where cavemen appear alongside dinosaurs – but this is much worse.'

A poster on the Palaeozoic era mentioned plants colonising the land, swamps, and the first tetrapods (so far, so good) but it also included humans in the picture: "The human population increases but remains localised to somewhere in fossil-poor Africa." Now, it incenses me that Lego produces a set where cavemen appear alongside dinosaurs – but this is much worse: humans alongside the first amphibians to pull themselves on to land?

In a separate building, there were more posters shoehorning geological eras into a young-Earth creationist story, along with a pretty impressive scale model of the ark, bigger than anything you've ever seen in a toy shop – more like a wooden container ship.

Noah's Ark presents its own particular brand of young-Earth creationism. As it says on its website: "We think that evidence shows the world is much older than 6,000 years but much younger than 4.5 billion years." One of the posters suggested that rates of radioactive decay were faster in the past, and this is why scientists have overestimated the age of the Earth.

There's a wilful subversion of scientific-sounding language too. The "earth history" page on their website opens with "Aspiring to an open, critical approach to explain what we see in the natural world." And yet none of the material I read suggested an even slightly critical approach to the religious text on which the whole edifice rested. I walked around, reading the posters, and feeling more and more incredulous: robust scientific facts were being distorted, bent out of all recognition, in order to fit with the religious story.

Now, you could visit Noah's Ark and not read the posters. But they're clustered by the picnic tables in the indoor play park – somewhere all the children are almost guaranteed to visit. But then, that's surely the real purpose of the place: you might think you're going there for a fun afternoon out, but you're really acquiescing in someone's attempt at a bit of light indoctrination.

I left knowing that I wouldn't want my children to go on school trips there. Why do I feel such strong antipathy? I'm pleased to live in a country where people are free to express their opinions, so why do I care so much about a few posters in a zoo? It's because, like Richard Dawkins, I believe that religious fundamentalism has the potential to ruin scientific education. Apart from obscuring scientific facts, it teaches a way of thinking that is incredibly rigid.

The evidence for a (very) old Earth and for evolution is overwhelming. But believing in these things isn't like a religious faith – it comes from a belief in evidence. The amount of scientific evidence stacked against the biblical creation story brings the scales crashing down in favour of an Earth that is billions of years old, populated by life forms that have evolved through natural selection. In order to believe the Bible account, then, you have to turn your back on that mountain of evidence. But it seems that, to persuade others, what you must do is take some of that evidence and twist it to fit the story. This is, purely and simply, subversion of science to fit a religious agenda. At Noah's Ark, you are not allowed to question the Bible. And where science and the Bible clash, every piece of scientific evidence is called into question, shoehorned into place if possible, or thrown out if it's too dissonant.

Its website says: "Educational field trips are a great way to learn… A school trip can encourage and consolidate learning in many areas of the National Curriculum." Teachers planning a school trip can visit for free, to familiarise themselves with the zoo.

In this zoo, the creationists have built themselves an impressive soapbox. I felt that I had to visit, if only to know what I would be excluding my children from if I stopped them going on school visits to this popular destination. I want my children to learn critical thinking, but the "critical approach" put forward by Noah's Ark is a disingenuous redressing of a centuries-old story which has its place in our culture but has absolutely nothing to do with science education.