That's true in the
  [1]https://en.wikipedia.org/wiki/Cataphatic_theology
  but not true in the
  [2]https://en.wikipedia.org/wiki/Apophatic_theology
  or negative theology (describing God only by what God is not).

  It's likely that Hume was unaware of apophatic theology as it's
  not part of the Catholic -> Protestant -> Rationalist -> Atheist
  tradition but rather part of the Eastern Orthodox Christian
  (middle eastern, not far eastern, although they had forays there
  too) theology.

References

  Visible links
  1. https://en.wikipedia.org/wiki/Cataphatic_theology
  2. https://en.wikipedia.org/wiki/Apophatic_theology