Births or conversions; it all adds up.'Islam' is growing by births, not conversion.
It's a bit of a stereotype: the goofy islamist convert attempting to use his religion to intimidate people. It happens a lot where islamists use the "fastest growing religion", nonsense as a subtle threat.
The comical part is that people such as Sunni man live in the West (and exploit the benefits of Western civilization) because their islamist paradises are foul backwaters of internecine hatreds, tribal rivalries, poverty and early death. People such as Sunni man are safely ensconced in their Western lifestyles and would no sooner live under the strictures of an islamist sharia state than others in this thread would.
There is nothing in islamist sharia state that allows for the personal freedoms, standard of living and freedom from religious oppression that Westerners frequently take for granted. We tend to think that the freedoms we enjoy are just the natural order of things. Most of us have never had to be concerned with religious police interfering in our lives or being hauled off to jail for some minor infraction of a Dark Ages theocratic code invented by a 7th century Arab warlord.
The worst nightmare a goofy convert could envision would be to actually have to spend time in the sharia state. That's why the converts choose to live under the protections afforded them by a secular constitution as opposed to living in a sharia state governed by bearded Loons in man-dresses.