Full Idea
Spinoza does not argue from the concept of God to his existence; he argues that a substance of infinite attributes cannot not exist.
Gist of Idea
Spinoza says a substance of infinite attributes cannot fail to exist
Source
report of Baruch de Spinoza (The Ethics [1675], I Def 6) by Beth Lord - Spinoza's Ethics 1 P11
Book Reference
Lord,Beth: 'Spinoza's Ethics' [Indiana 2010], p.29
A Reaction
Lord is explicit that this is NOT the argument used by Anselm and Descartes. I'm not clear why there has to be a substance of infinite attributes, but presumably that is explained somewhere.
Related Idea
Idea 21858 God is being as such, and you cannot conceive of the non-existence of being [Spinoza, by Lord]