“In the year AD 2293, a post-apocalypse Earth is inhabited mostly by the “Brutals”, who are ruled by the “Exterminators”, “the Chosen” warrior class. The Exterminators worship the god Zardoz, a huge, flying, hollow stone head. Zardoz teaches:

The gun is good. The penis is evil. The penis shoots seeds, and makes new life to poison the Earth with a plague of men, as once it was, but the gun shoots death, and purifies the Earth of the filth of brutals. Go forth . . . and kill!

“The Zardoz god head supplies the Exterminators with weapons, while the Exterminators supply it with grain. Meanwhile, Zed [as in the last letter of the English alphabet] (played by Connery), an Exterminator, enters Zardoz, hidden in a load of grain, and shoots (and apparently kills) its pilot, Arthur Frayn (Niall Buggy) (identified as an Eternal in the story’s prologue), and travels to the Vortex. The Vortices are hidden communities of civilization where the immortal “Eternals” lead a luxurious but aimless existence.

“Arriving in the Vortex, Zed meets two women Eternals — Consuella (Charlotte Rampling) and May (Sara Kestelman) — with psychic powers; mentally overcoming him, they make him prisoner of their community. Consuella wants Zed destroyed immediately; others, led by May and a subversive Eternal named Friend (John Alderton), insist on keeping him for study…”

Zardoz synopsis Wikipedia
Zardoz title image Mr Bali Hai’s Psychotronic Titles