I was going to make this point…

…but Jib beat me to it:

Islam has overtaken Roman Catholicism as the biggest single religious denomination in the world, the Vatican said on Sunday.

Monsignor Vittorio Formenti, who compiled the Vatican's newly-released 2008 yearbook of statistics, said Muslims made up 19.2 percent of the world's population and Catholics 17.4 percent.

"For the first time in history we are no longer at the top: the Muslims have overtaken us," Formenti told Vatican newspaper L'Osservatore Romano in an interview, saying the data referred to 2006.

Jib writes:

Why is the Vatican comparing the whole of Islam to Roman Catholicism? Islam is not without its theological divisions. Sunni, Shi'a, and Sufi are all Islamic 'denominations', if you will.

Yeah, it's kinda like comparing one team's passing touchdowns to another teams total touchdowns.

I wonder what the context was: why would the Vatican go out of their way to let us know that?