- 9/11 was organized/enabled/allowed to happen by actors within the US Gov.
- Pearl Harbor was organized/enabled/allowed to happen by actors within the US Gov.
- JFK was assassinated by the CIA
- All history from CE 614 to CE 911 was fabricated by the Holy Roman Empire
I'd say 4 is just as easily disprovable as flat-earth-ism: There are other, contemporary societies in contact with Western Europe who were also keeping track of time... unless there was an Eurasia-wide conspiracy (in CE 1000) to fabricate those years, the dates only line up the way we count them now. There are also well-established (and recorded) astronomical events that line up well with the commonly-accepted timeline (but that would take believing that astronomical events are predictable by science).
In all, I'd say it's much more likely that NASA pretended to land on the moon than that the century we think Mohammed lived in didn't happen.
EDIT: Misread my own numbering