Do I really have to explain things for you?

Read the quote I replied to.
Kyser-soze defines being religious as believing in the Christian idea of God, as mentioned in the Bible. If he didn't, he wouldn't have used that data given to back up his arguement that the USA is more religious than the UK.
He could have used census data, which gives a more detailed picture of not only how many people are at least culturally Christian, but what the religions (or religious affiliation i.e. which one you'd go for if you had to choose one) of the population are.
Christianity is a religion, not the religion. Alles klar?