The ongoing debate over faith schools is largely conducted at the level of, well, faith. Most of us have an instinctive opinion about whether it is a good idea for churches, mosques and synagogues to have a hand in educating young people. David Cameron, like Tony Blair before him, believes religion fosters a “culture and ethos” that supports learning. Many an atheist would disagree, as would devout believers such as Rabbi Jonathan Romain who want to see faiths mingling, as opposed to pupils being clumped together on the basis of creed.Gut instincts about whether faith schools should exist in the first place colour all judgment on the secondary question about how well they serve the poor. Every middle-class Londoner hears tales of godless parents suddenly attending church before putting their child up for a thriving school where this helps. But religion is one of civil society’s surest routes into poor communities, and there are devotees – including some faith school teachers and sponsors – who radiate a commitment to help pupils from the bottom of the heap. So there are enough anecdotes about both posh parents playing the system and poor kids being touched by divinely inspired instruction to cater for all prejudices. Naturally, this position fuels a debate that leads nowhere.Enter the database of English faith schools, which the Guardian releases today. It at last allows the official numbers to be crunched – so we can see what sorts of pupils attend faith schools, but crucially also how these compare to the wider mix of pupils locally. The picture is varied, but worrying overall. There are plenty of individual faith establishments which do take more than their share of the poor, and tentative signs that schools connected to poorer faith communities – evangelicals and Muslims – reach right down to the dispossessed. But most Anglican schools do appear disproportionately to serve the better-heeled parts of their communities. For Catholics, who have made great play of their inclusion and successively fought to control influence over admissions, the results are even more skewed.There are of course noble exceptions, but overall the data points to pausing for thought before sanctioning a dash for more faith schools. There are many complexities: where councils and churches both have a hand in school management things can get even more elitist than when a church is in sole command. Understanding such patterns will take much more detailed work, but is indispensable if lessons are to be learned. Too many academic papers meekly conclude with a request for another research cheque. But when too many faith schools work for the few, it has to be worth investing a little in understanding exactly why some work for the many, before pouring any more serious cash into setting up more.