Full Idea
If God works to obtain an end, He necessarily seeks something of which he stands in need.
Gist of Idea
God has no purpose, because God lacks nothing
Source
Baruch de Spinoza (The Ethics [1675], IApp)
Book Reference
Spinoza,Benedict de: 'Ethics', ed/tr. White,WH/Stirling,AH [Wordsworth 2001], p.38
A Reaction
The point is that a being with infinite attributes cannot be in need of anything, and hence God merely exists, but does not have a purpose. Hence falling in line with God's purposes cannot be an aim of a human religion.