Monsignor Vittorio Formenti, who compiled the Vatican's 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 the Vatican newspaper L'Osservatore Romano, saying the data referred to 2006.
He said that if all Christian groups were considered, including Orthodox, Anglicans and Protestants, Christians made up 33 percent of the world's population, or about two billion people. The Vatican recently put the number of Catholics in the world at 1.13 billion. It did not provide a figure for Muslims, generally estimated to be around 1.3 billion.
Update: This is my 200th post!! hurray!! :)