Odious, despicable, hypocrite – those are just a few of the words that have been used to describe me since the publication of my book School Daze: Searching for Decent State Education. My sins? There are two, according to my critics.

The first is that I faked being a Christian to get my children into the local Church of England primary school. My plea: guilty. I am an atheist, but for at least two years before my son reached primary-school age I went along to the local church, along with my wife. And so it came to pass that our son got the school place.

My mitigation is this: whose fault was it that we had to go to church to get our son into the local primary school? I didn't choose the selection criteria that meant that half the places were reserved for churchgoers, thus discriminating against local families who did not follow this particular brand of religion. This was not a situation of my choosing. I went to church under duress, because that was the only way to be sure of a place, even though that school was literally the other side of the road from our house. I didn't pretend to be a Christian for several years because I wanted to offend anyone, or because I thought it was fun – I promise you it wasn't. I did it because I wanted my son to attend the local state primary school. Is that too much to ask?

Christians who are offended by my behaviour – and I've heard from plenty – perhaps need to become a little more realistic, because every Sunday across the country churches are full of families doing exactly what I did. If churches do not want bogus Christians coming through their doors there's a simple solution: stop using religion as a criteria for admission to state schools.

We live in a secular society. Depending which survey you read, roughly 900,000 people attend Anglican mass each Sunday in the UK, and the figure for Catholic mass is similar. That's out of a population of more than 60 million. Why do we allow such tiny minorities to have such sweeping control over our state education system?

Those figures for churchgoers mask the true position, because many of those filling places in church each Sunday will be unbelievers like me who are only there because they care about their children's education. That's why churches will not be advocating an overhaul of the education system: they can use their control over school admissions to get heathens through their doors each Sunday.

It's an abhorrent situation, and one that is made worse when parents are forced to play a system that they didn't create and are then accused of being odious, despicable hypocrites.

So, on to my second sin. I didn't send my son to the local comprehensive. There are those, if I've got the argument correct, who think parents should send their children to the local secondary school irrespective of how that school is performing. Parents who get their children into grammars or move closer to better schools are, apparently, condemning their local comp to eternal failure. This is an argument that has its logic back to front. Poor schools are the cause of families looking elsewhere for their children's education, not a consequence of it.

When we began looking at the state secondaries near our then home in Merton, south-west London, just one third of pupils at the nearest one achieved five or more GCSEs, English and maths included, with a grade C or better. By the time parents were selecting comprehensives last winter, the results had gone up to 49 per cent. A great improvement, but I wanted better for my child – and I was not alone. The father of a child still at the primary school my son attended tells me that just two boys from this summer's leaving year went on to that local comprehensive.

Overall in Merton, one third of children at its primary schools do not go on to its secondaries. Some families move house, some find the money to go private, some get places at grammars in nearby Sutton and Kingston.

"In my circle of friends, I know probably half a dozen people who have moved specifically to be in the catchment area of schools," I was told by Dave Hill, then Merton's director of Children, Schools and Families. "It's like a national disease.I make no judgment. The system is set up in such a way. I hope we can persuade people like you in the future to see the results, see what's happening here, and say 'I'm going to stay in Merton, I can get a good education here.'"

He also candidly told me: "I do think that if you live in any area and you've got a school that's not scoring around 60 per cent, I don't know if I'd really want to send my kid to that school. And I think people have a right to choose something else. We've had schools down in Mitcham scoring 18, 15 per cent – it's just not acceptable. Why would your want your bright kid, with all your family support, to go to a school where clearly that school is not going to be able to improve [his or her] chances? You'd be mad to."

One of the schools that is improving is the local comprehensive – Rutlish – that I was so keen to avoid. Its GCSE results for 2010, as yet unpublished, have gone up to 61 per cent. I'm delighted to hear of this transformation, I'm glad to hear of any school improving, because at the heart of this problem is that fact that there are too many dreadful schools that caring parents are understandably desperateto avoid.

During my research for School Daze I encountered an interesting divide. Pretty much everyone I interviewed in Merton, the borough I abandoned, disapproved of my actions. One comprehensive head told me I'd wasted my time, though he was kind enough to add: "But I understand why you've done it. There are thousands of people who've done what you've done, or who will subject their children to enormously long journeys to get into certain schools. Lots of more able children leave after year six or go into private education. Friends of mine have not sent their children here. I understand that. We still get on."

Conversely in Surrey, where we now live, there was universal approval, one headteacher even admitting that he had once moved house because he didn't think the local primary suited his children.

Back in Merton, a regular at the church I once so diligently attended recently emailed me, mainly to accuse me of "conning and lying" to get my children places at the local Anglican school and "proudly admitting you exploited the old and infirm" (I had volunteered for the car rota to help the elderly get to and from church).

He then went on: "Funnily enough, it now looks as if the joke is on you because you have spent 40k on moving house to a so-called posher area where your new local comp only has a 2 per cent better GCSE pass rate than Rutlish."