Monty Python’s Life of Brian
United Kingdom
1979
After slaying the Arthurian legend in their now classic Holy Grail, the Pythons set their sights on the Greatest Story Ever Told. Blind faith, virgin birth, crucifixion—nothing is sacred in this epic send-up of ancient times, which draws on the cornball biblical blockbusters of the 1950s to lampoon celebrity culture in any era. Criterion has gathered the guilty parties—including John Cleese, Terry Gilliam, Eric Idle, Terry Jones, and Michael Palin—for two commentary tracks as provocative and hilarious as the film itself. —The Criterion Collection

The funniest film of all time, no contest. Probably the scope of the subject and the success with which it is tackled justifies the claim, although some Xtians may disagree.
The genesis (I know… read review