Belloq says it when he looks into the golden glow of the ark in “Raiders.” Pumpkin says it when he looks into the golden briefcase in “Pulp Fiction.”
It seems like whenever the protagonists are at a crucial point in either film, the predominant color the directors use is gold.
McGuffin? Grace? Power? Dirty laundry? The wrath of God?
My best guess is a metaphor for “something of value” — something so valuable people will kill for it.