The aim of More than an Educated Guess, the new report [PDF] from Christian think tank Theos, is certainly laudable – it promises a “cool headed reassessment of the evidence base” around faith schools. Anyone who's observed the debate over religious schooling knows that it's too often characterised by hyperbole and, at times, outright dishonesty, so Theos should be applauded for its ambition. But what it promises and what it delivers are two very different things.

Let's start with what, for readers of this site at least, should feel like a vindication. The report's authors accept that there is “some evidence of indirect socio-economic sorting” at voluntary-aided faith schools (those which have the most autonomy from local authorities) and that their much-lauded academic achievements are “probably primarily the outcome of selection processes”. For an organisation like Theos to acknowledge, however grudgingly, that faith schools have skewed intakes – and to urge faith schools to reassess their admissions policies – should be welcomed.

As the British Humanist Association has meticulously noted [PDF], however, the report's credibility is undermined by a series of errors and inaccuracies. It exaggerates the controversy surrounding free school meals (FSM) as a measure of disadvantage, for example, suggesting that pupils in Catholic schools may not be taking up FSM due to parental pride (an interesting idea, but irrelevant – FSM rates are an estimate of eligibility not take up). The authors also quote from an old version of the admissions code and seem to be unaware the Citizenship is a national curriculum subject.

Too often the report puts words into the mouths of faith school opponents. I have never heard a serious secularist refer to “education apartheid” in Britain, yet the report implies this is a common complaint. And it grossly caricatures the secularist vision for education as one in which we must all “disregard our religious, philosophical and cultural identities”. Conversely, it takes the claims of religious organisations at face value – and its potted history of the church's involvement in education is entirely uncritical: “faith schools ... began with a mission of ameliorating poverty and inequality by providing education for all.”

The authors are right to highlight the difficulty in assessing the impact of faith schools on what politicians like to call “community cohesion”, but to do so they rely on a misrepresentation of Right to Divide? [PDF], the influential Runnymede Trust report which was actually highly critical of religious selection.

Perhaps the report's biggest flaw is its limited scope. Its authors choose not to examine what is actually taught in faith schools, despite this being one of their opponents' main grievances. Most faith schools are permitted by law to teach confessional religious education (i.e. instruction) and can also teach sex and relationships education from a religious perspective. What impact does this have on the quality and breadth of the education they provide? The report brings us no closer to an answer (though Theos does intend to explore curricular issues in the future).

Nor does it address what for me are the most important questions in the faith schools debate. Why, when it is unacceptable (and often illegal) in every other public service, do we allow religious discrimination to thrive in our education system? Why does public money go to schools that can select children – and hire and fire staff – on the basis of perceived religious belief?

The authors of More than an Educated Guess seem well aware that such moral concerns cannot be resolved simply through more research. “At base, this is not a debate that can be decided on evidence alone, but is also about the kind of society we want to live in,” it says. (And it seems most of us don't see a place for faith schools in that society – only a third of the public approve of them.)

By far the most intriguing aspect of the report is its plea for all sides to “acknowledge the partiality and contested nature of many of the conclusions” and to be more honest about the “true points of tension”. Had they fleshed out these recommendations into a full argument they may have made a more meaningful contribution to an increasingly polarised debate.