Begotten(1990)

The story opens with a robed, profusely bleeding "God" disemboweling itself, with the act ultimately ending in its death. A woman, Mother Earth, emerges from its remains, sexually arouses the dead body, and inseminates herself with its semen. Pregnant, she wanders off into a vast, barren landscape. The pregnancy manifests in a fully grown convulsing man whom she leaves to his own devices.

via TheTVDB