[sudosysgen]

The math doesn't work though. 50% defection rate and only 50% higher birth rates won't work. If the average woman has 2 children, the religious subgroup one would have 3. On average, 1.5 of those would defect, so the average woman produces more members of her group.

This is borne out by the data. If you look at the ASRI, from 1990 to 2008, the percentage of LDS (and other similar groups) has remained stable in the US.

Only Islam and Buddhism saw (very minor) growth, the rest was a massive surge in secularism.