Why are Muslims the world's fastest growing religion?

[Dakota Schaefer]

"Muslims will grow more than twice as fast as the overall world population between 2010 and 2050 and, in the second half of this century, will most likely surpass Christians as the world’s largest religious group."

Source: http://www.pewresearch.org/fact-tank/2015/04/23/why-muslims-are-the-worlds-fastest-growing-religious-group/