Star Trek 5: The Final Frontier (1989)

Vulcan cult leader Sybok and his followers have invaded a 'planet of peace,' where delegates from hostile races coexist in a sort of intergalactic United Nations. Spock's half brother hijacks the Enterprise for an obsessive search for God. He also believes that God lies beyond the Great Barrier. Once arriving there, however, Sybok and the Enterprise crew discover only an imprisoned alien entity.