It's kind of the point, in two ways. First, the constant usage of the Bible to justify political discourse is both a staple of the USA and also painfully stupid. It doesn't matter how nice of an imaginary picture is painted by the "city upon a hill"; it's still a religious and rose-tinted portrait. Exodus probably didn't happen, and so it is a nice story (like Harry Potter) but not worth bringing to the policy table.
Second, the Bible is just not very well-translated. Consider this instead:
> You are the salt of the earth.
> Your flavor brings merit and mirth.
> But use too much extra, anybody could tell ya
> Oversalted food has no worth.
> You are the light of the world.
> Like a town on a hill, you are pearled.
> But in light we bask, only while it's unmask'd
> So fly your town's flags high and unfurled.
Still terrible, but at least now it rhymes correctly.
Second, the Bible is just not very well-translated. Consider this instead:
> You are the salt of the earth.
> Your flavor brings merit and mirth.
> But use too much extra, anybody could tell ya
> Oversalted food has no worth.
> You are the light of the world.
> Like a town on a hill, you are pearled.
> But in light we bask, only while it's unmask'd
> So fly your town's flags high and unfurled.
Still terrible, but at least now it rhymes correctly.