The big problem is, when the leader of these cults dies or gets whacked, the following dies then or soon thereafter. The gospel truly has a life of it's own, or should I say the life of God in it. Otherwise, it would have died out like the cults you mention.
History does not bear this out. As an example William Miller died in 1849, however today we have over half million Adventist and 7th day Adventist following a modified version of his teachings.
The reason Christianity and Islam continued so long is each was useful to a evolving State. Christianity was adopted as the official religion of Roman Empire under Constantine, and Islam as the official religion of the Arab Empire that took over the middle east, north Africa, and half of Spain.
It was their utility to secular powers, not supernatural powers that lead to their long term success.
Catholicism ended in England when it was no longer of use to the reigning monarch, Henry VIII.
You didn't use logic or reason to get into this opinion, I cannot use logic or reason to get you out of it.
You cannot over estimate the unimportance of nearly everything. John Maxwell
