Though many of the cast and crew were zonked during production, there is actually some serious science fiction in Zardoz.
In a nutshell, the world is descending into chaos, for unspecified reasons, so a group of idealistic scientists create somewhat self-sufficient enclaves behind nearly impenetrable force barriers, and devise a way to make themselves and their children immortal.
The people inside the enclaves call themselves immortals, and the humans outside, brutals, and have also created a cult of brutal killers, called exterminators, to cut down on the number of brutals, lest they figure out some way of breaking into the enclaves.
One of the immortals realizes that the world has become stagnant, that the immortals have reached their maximum intellectual abilities, and the only hope is to spend generations breeding a mutant (Connery), who can bust up the status quo. Who can intellectually go far beyond the immortals, and ruin the great AI computer that keeps them forever alive.
I finally understood the movie about the third time I watched it. Still one of the weirdest movies ever.