The proposition "higher mathematics is useful" can be communicated to people with negligible mathematical training, along with specifics and supporting evidence. Higher math is required to describe the physics that can figure out from first principles how chemistry should work, and somewhat lower higher math can figure out the area under curves and so forth.

In particular, a person who knows no math can observe that people who know higher math are required in order to do chemistry simulations, for example.

Is there a similar easy way to make a claim that enlightenment is useful that is testable by unenlightened people?

(For the record, I'm inclined to believe you, but it would be comforting to have a concrete argument for it.)