I wish the islamic data give you idea. Islam  growing each year 0,12 ,  of course Christianity grow to only 0,02 if it’s go like that after 150 years Islam become biggest religion on the world. They worry this point and other problem the 0,12 growing rate growing to . But Christianity grow rate come down they can’t grow somehow lose. Roman Catholics lose more people this way.  If 150 years become 50 think again... Note: all value lovely dollar