Nicely done, in your habitual fashion of using quotes out of context. Why, you ought to see if David Barton is hiring!
But let's look at your quote in context, as I admire both Hume and Jefferson greatly, no matter that they were opposed on some matters and the way he refers to his previous hero as "degenerate."
Note first of all that the quote is referring to "origin of just powers," not morality.
Second, note that the point is not what Jefferson, himself, believed, but he's pointing out that Hume must trace back to the majority to support his side (I wish I could recall the strong adjective Jefferson applied to Hume's Tory leanings elsewhere in the letter).
Finally, we all know this quote is a favorite of leftists trying to bypass the Constitution and advocate turning our republic into a democracy. Are you advocating democracy or theocracy? I hate to tell you, but a democracy would not lead to the great theocratic rule seem to hope to impose.
justMoral is not moral; A is not A.adjective: of moral excellence
Another excellent example of Randian doublethink.