A few Genseis questions... "You will surely die"... Please explain "die"?

[Dachaser]

Is it necessary to assume that Satan is telling the truth in his insinuation that they were not like God? I believe Satan was lying in said insinuation. When he said, "You will be like God," the lie was in the insinuation that they were not like God, but would be if only they would eat of the tree. How could they be made in the image of God and have zero knowledge of good and evil? This does not make sense to me.

Their real big mistake was not fully trusting in what God had told them to do, as when they opened it up to listening what Satan wasl saying unto them..