I was walking home from a bar last night (first time I had gone out to shoot pool in a long time!) and I had an imaginary theological conversation in my head. I do this pretty often, envisioning discussions that could occur after someone cites a prooftext taken out of context that has nothing to do with the point being discussed. I don't get to have these in real life often because I don't hang around proselytizing evangelicals very often any more.
Anyways, the verse I had in mind was Ezekiel 18:4 or Ezekiel 18:20. A snippet of the first says "The soul who sins will die." The other says "The person who sins will die." They could each be used (and have been used) to suggest that death is the appropriate punishment for any sin.
But that isn't what Ezekiel 18 is saying at all. Ezekiel 18 is laying out that the punishment for sin will lay on the sinner rather than his offspring. Furthermore, it is indicating that righteous conduct done in the past does not insulate someone from the danger of death as punishment for sin in the present. It is most definitely not saying "Once someone has sinned one time, that person is subject to death." Indeed, Ezekiel 18:21-22 (among other places) indicates the exact opposite:
But if the wicked man turns from all his sins which he has committed and observes all My statutes and practices justice and righteousness, he shall surely live; he shall not die. All his transgressions which he has committed will not be remembered against him; because of his righteousness which he has practiced, he will live.
The realization I made last night is that this whole chapter argues against one interpretation of Original Sin. Some people believe that we are actually liable for the sin of Adam because Adam is the father of humanity. The whole point of Ezekiel 18 is that one generation is not punished for the sin of its ancestors.