NOT AT ALL.
It's a geometric progression.
When a desperate-for-hope people find Substance to have hope in--especially in a COMMUNITY/FAMILY unit oriented culture--it spreads like wild fire.
They eagerly want everyone they know to have some of this new bread, this new gold that gives them hope for the first time in their lives.
You still obviously speak out of your poverty of first hand experience and observation.
It would have been entirely possible for there to have been 3 million or 7. It's a rapid increase but not as fantastic--given all the givens--as you make it out to be.
In China, whole villages could become Christian in 72 hours. Authentically--ready to die for their faith--Christian.
I am certainly not one to deny the power of Christ! Of course that is true. They could. Many probably have. But, as I stated above, China is very different from an Islamic society.
My deep objection is to the parenthetic addition to the title--it is manifestly untrue.