Isn't the Celestial chariot originally of a pagan origin? Egyptian beliefs have the sun being dragged across the sky by a fiery sort of horse drawn chariot. Other; old faiths have something like this too. The GB is using pagan analogue to promote a faith, using a slogan. Wonderful, riveting stuff
I know there is mention of chariots in the bible, but this is not the oldest source of such a thing. It is pre dated by many other cultures.