I don't think you can compare Muslims to Christians in this respect brit. Islam is literally a way of life for Muslims, which isn't the case for Christians. I don't know many Christians who think you're not a Christian if you don't follow Christianity precisely.

My point about the percentages was that the statistics show that there are a huge amount of Muslims in the world, but these figures are probably wrong if you take Islam's own logic that anyone who doesn't follow Islam precisely isn't a Muslim.