Ha ha this looks like the Census survey in the UK that enumerated the Christian and other minor faiths into nearly every possible flavour but lumps the "non-religious" into one big category.

The UK census results said that "About sixteen per cent of the UK population stated that they had no religion. This category included agnostics, atheists, heathens and those who wrote Jedi Knight. "

Now how the fuck do they know that ?. They didn't have a checkbox to indicate if you were "atheist", "heathen" etc. They are just guessing.

If they had lumped the Non-Christians and then said "About x per cent of the UK population stated that they were non-Christian. This category included Sikhs, Hindus, Jewish and Muslims...." then the shit would hit the fan.