How many people say they are a christian?

Answer 1

As of the early 21st century, Christianity has around 2.2 billion adherents within the world population of about 7 billion people. However, one must question how many of these are adherents simply because they were born into the faith as opposed to a rational choice of belief. So the answer to your question of how may people 'say' they are Christian could not be answered without polling all 2.2 billion supposed adherents.