See, I don't see suffering and death as necessarily linked to sin. We do not suffer more because we sin more, or less because we sin less, and we certainly don't die less.

What we suffer is true pain and death: separation from full communion with God. For this, we need redemption due to our sinful nature. We need something to bridge that gap. Jesus came to "undo" the damage caused by the Fall, correct? Well, what DOES that redemption do? Does it undo pain and suffering? No, those who accept that redemption still physically suffer as much as those who reject it. Does it undo physical death? No, we all still physically die. Since we KNOW that Christ's act of redemption was effective and that He did His job fully, we know that job can not have been to do away with physical death and suffering. Instead, we see that it does away with spiritual death and suffering. It allows us to be back in full communion with God. It allows us to spend eternity in that full communion. Thus, working backward, we can see that if Jesus' work was to undo what happened at the Fall, then what happened then must have been this spiritual death, not physical. And this happens to fit as well with the "and on that day you shall surely die". Also keep in mind that even those who reject Jesus will live forever. ALL of us have eternal physical life, it just depends on where we are going to spend it.