You should read Scripture before quoting it. Here's the second half of Genesis 2:17, in various translations:
King James - "for in the day that thou eatest thereof thou shalt surely die."
Revised Standard - "for in the day that you eat of it you shall die."
New American - "the moment you eat from it you are surely doomed to die."
I was initially looking at New American, but the other two -- the two most widely accepted versions -- clearly say he'll die that very day.
It looks like from Theo's original quote that he uses the English Standard Version. Here's Gen 2:17 from that one:
"but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat[a] of it you shall surely die."
Be aware that the [a] footnote in this version offers up 'when you eat' in place of 'in the day that you eat', apparently because someone took it upon themselves to edit God's word to remove the problem of a literal day reference.
We could go around and around with this verse. Yes, on the day that Adam ate the fruit and sinned against God, God doomed Adam to die. I would argue that if he hadn't sinned, he would not have died.
But let me ask just a few questions, to help get us out of this loop:
1) Do you believe Adam and Eve would have died if they hadn't sinned?
2) How do you interpret Romans 5:15-21, which clearly states that "the many died by the trespass of the one man" and that "by the trespass of the one man, death reigned through that one man" and "sin reigned in death"?
3) And how do you interpret Romans 8:18-22, which speaks of a bondage to decay brought about by the Fall?
4) In light of Romans 6:23, would you say that death is *not* the consequence of sin? Yes, "spiritual" death, but also "physical" death. Death.
Great examples of how "day" is not necessarily literal in Genesis.