People are always going to demand kooky explanations for those things they value most. Better they find what they want in Scientology than Islam. I've never known a Scientologist to blow himself up in a crowded coffee shop.
_Stranger in a Srange Land_ gives an interesting spin on this idea.
There's a big difference (imho) between scn & islam - scn costs
a lot of money, which limits access by the masses. Islam seems to be much easier to "spread", seeing how it seems to require only access to a koran and a local leader (ok, as well as maybe a prayer rug and a compass).
Also, scn seems to carry out it's dirty work via a central organization (flag), whereas islam relies on individuals to blow themselves up or fight.