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