Islam is currently fastest growing religion. What about irreligion?

[Fidel_Castronaut]

I've often thought that the reply to the question 'Do you believe in any God or gods' is all you need to determine the number of atheists. Any other question makes it more likely your assessment will be confounded.

Nominal Christianity in the UK is the biggest reason why the official census results reflect such a high proportion of people who identify as Christian.

As apo's quote says its the cultural aspect that informs the answer more than the actual belief.