When Muhammad died, every single person left Islam, except for three towns: Mecca, Medina, and Ta’if.
The vast majority of Arabs who had professed Islam under pressure, conquest, or political convenience walked away without hesitation.
If it weren't for the wars that followed, the brutal Ridda Wars, in which an estimated 70,000 people were killed, Islam would have disappeared into the dust of forgotten ideologies.
Abu Bakr, Muhammad’s immediate successor, understood what was at stake. If Islam was going to survive, it had to be enforced, with steel, not sermons. So he declared war on all who had left.
Entire communities were wiped out. Apostasy was met with the sword.
This moment in Islamic history, the Ridda Wars, is well-documented by early Islamic historians like al-Tabari and Ibn Kathir.
Islam spread, survived, and was sustained by violence from day one. If Abu Bakr hadn’t launched a campaign of coercion and extermination, Islam would’ve died the same way it was born: through blood.