more fiction from the left
It is wrong, Islam isn't by far the fastest growing religion
From the 1991-2001 The Religious Identification Survey (Large .PDF warning)
Muslim/Islamic did double their numbers from 527,000 to 1,104,000 but in terms of % it is only an increase from 0.3% of the population to 0.5%.
A few of the Christian Religions grew more in people or % like the Catholics, Pentecostals and Evangelicals and over all while Muslims only increased by 500,000 Christians as a whole increased by 8,000,000 though as a percent of the population Christians declined nearly 10% from 86.2% to 76.5%.
The fastest growing Religion in % and numbers is of course No Religion
Atheist, Agnostics, No Religion made huge gains and went from 14,331,000 people at 8.2% of the population to 29,481,000 which 14.1% of the population