God knows everything, but somehow he didn't know that this one tricky serpent
1) Existed in the first place
2) Was in his garden

He also punished the human couple instead of the serpent for some weird reason.
And not only it was lifetime punishment but it extends to every single generation until the end of time unless you "repent" on behalf of your grandx20-parents, because stealing an apple is much eviler than say torturing and executing a bunch of heretics