He did NOT say...
Genesis 3:22 And the LORD God said, Behold, the man is become one of us, to know good and evil:
Oh, he didn't?
Dude, (Mormon variety ;-0) you really need to not post scriptures like that before reading them in order to prove your point, they do just the opposite. Let's look at both passages again, and I will bold and underline them to show you where you err.
Genesis 3: 5 (SATAN TALKING HERE)
5 For God doth know that in the day ye eat thereof, then your eyes shall be opened, and ye shall be as gods, knowing good and evil.
Genesis 3: 22 (GOD TALKING HERE)
22 And the LORD God said, Behold, the man is become as one of us, to know good and evil: and now, lest he put forth his hand, and take also of the tree of life, and eat, and live for ever:
Let's be clear about what they both said, both used the phrase "as Gods", or "as one of us"
you were saying...?