"Globally, Muslims have the highest fertility rate, an average of 3.1 children per woman—well above replacement level (2.1) due to young age of Muslims (median age of 23) compared to other religious groups."
"Islam is the fastest growing religion all over the world,
[4] due primarily to the young age and high
fertility rate of Muslims."
" it is predicted that the world's Muslim population will grow twice as fast as non-Muslims over the next 20 years. By 2030, Muslims will make up more than a quarter of the global population. If current trends continue, it is predicted by the year 2100 that about 1% more of the world's population will be Muslim (35%) than Christian (34%)."
https://en.wikipedia.org/wiki/Muslim_population_growth