Sure the near death person may have filled out a donor card and if they didn't, the next of kin can make the decision to donate their organs. Religious beliefs have always fought with science. Luckily science and good judgment have won over traditional religious beliefs or society would still be trying to heal people with witch doctors putting strings of garlic around your neck. Medical advancement shouldn't be held back because some people have a difficult time understanding humanity. If stem cell research can lead to cures for Alzheimer's disease, Parkinson's disease, heart disease, diabetes or the many other diseases, then society is obligated in using embryos to help the living.
Embryos are like presidential candidates.
Under the right circumstances they might develop into something. Until they do, neither should be given all the rights and privileges that go with what might be and both should be used for medical research.