Buried on page 59 was the chart I needed for the correct analysis:
It shows the Christianity will only match population growth projections with some last minute growth near 2045 - 2050. There were more interesting tid bits to delight the data hungry detail folks about the religion "switchers" (from one religion to another - or to none). Over the 40 years it is projected 40 million will switch into Christianity and 106 million will switch out - and predominately men (over 60%).
So .......as B.E. would say, "What are YOU going to do about it?
Change the assumptions or change the actions?