Judaism is the only religion in history that claims that G-d spoke to the whole nation.
All other systems start with one person or a few people — Buddha, Mohammed, Paul, Guru Nanak, Joseph Smith - who heard G-d or found enlightenment and then convinced everyone to follow them.
Why did no other religion in the history of the world come up with the same, much stronger, claim of mass revelation?
Is it because it is impossible to get away with this claim if it didn't really happen?
And if someone did pull it off in a natural way, how could they guarantee it wouldn't happen again?
Skip to 12:16 for the beginning of the argument