"Black Cube" - wonder what they're going for there. Maybe "Sinister Obelisk" was taken.

It's Saturn worship. Judaism is Saturn worship (all Abrahamic religions incorporate some worship of Saturn) - thus the obsession with black cubes, the number six, etc... There is no Star of David in the Bible - only the star of Remphan (a Saturnian deity). The god El is commonly associated with Saturn and commonly referred to as Saturn El. Saturn is the planet of limitations, constraints, agriculture, grain, the color black, etc... Thus the black cube is very fitting. If you look around hard enough, you'll find the symbolism everywhere.

https://en.wikipedia.org/wiki/Remphan

Remphan - Wikipedia

Isn't Islam the one with the Black Cube?

Judaism also has important black cubes in the form of tefillin worn by adult male jews during one of their daily prayers on weekdays.

https://en.wikipedia.org/wiki/Tefillin

Tefillin - Wikipedia

Yes, the kabba is also a nod to Saturn (which is why I said all Abrahamic religions incorporate some Saturn worship into them), and the people walking around the kabba make the rings of Saturn (if you employ some time-lapse photography of them walking around, it's quite obvious). Saturn has a hexagonal shaped storm on its north pole (and the all-seeing eye on its south pole). If you collapse a cube into two dimensions, you get a hexagon.
Ok, maybe put the hat back on. At least the abrahamic religions hardly knew about the hexagonally shaped storm.