Critique of Premise 1
Hume says that every idea can be analyzed into simple ideas which are copied from impressions, but he offers at this stage only one example. Surely a critic could contend that for all Hume has argued there are some ideas which can't be analyzed in this way. [defense]

Critique of Inference
To the extent that this is to be understood as an inductive argument (as I have suggested here), it is surely weak since it proceeds from but one example, that of the idea of "God."

Defense of the first argument against the critique
Hume does offer us in this section one example of an idea derived from impressions. While we might want more, the example he offers is at least an important one: our idea of God. This is important because many of those whom Hume is concerned to refute (in particular Descartes -- see Meditation III) would take that idea to be innate and not derived from impressions.

Hume argues that the idea of God is derived from impressions. Which impressions? Not an experience of God, interestingly enough.[footnote 1] It is derived from inward impressions of the "operations of our own mind" and in particular our ideas of our own goodness and wisdom. These ideas are then "augmented without limit" and combined to yield the idea of God. [text]

Evaluation of first argument in light of critique
Hume recognizes that what he has offered here, although he calls it an "argument" [text] is really more of a challenge. [text]