This last point some religious groups vigorously dispute. While they agree on the obligation to try to cure diseases, they say proponents are touting benefits that are uncertain and lie far in the future. The scientific community and biotech industry encourage the sense of inevitability because they don't want limits set, some say. Most important, the religious groups add, other morally acceptable means are available that should be explored first.
"It's a question of conscience," says Richard Land, president of the Southern Baptists' Ethics and Religious Liberty Commission. "To compel millions who find such research unconscionable to support it with our tax money is abhorrent."
The National Institutes of Health's recent report said research is needed with both embryonic and adult stem cells because the former holds the possibility of accomplishing more things.
But Catholic, Southern Baptist, United Methodist, and Episcopal churches say the emphasis should be on adult stem cells, for which numerous clinical uses have already been discovered.
To families awaiting the potential benefits from embryonic research, Mr. Hanson says, "My father has Parkinson's and diabetes, and my mother has Alzheimer's - so I understand what it means to grasp at any hope. But it's also important not to confuse one strategy with the goal."
Not all opposing churches share the Catholic and Southern Baptist view that a human person is created at the moment of conception.
But they say early human life deserves moral respect, and therefore this strategy requires deep ethical exploration.
Lutheran ethicist Gilbert Meilander argues that the moral reasoning fundamental to "just war" is pertinent to the stem-cell debate. In this reasoning, a "supreme emergency" must be present both to go to war and to use strategies that otherwise would be ethically unacceptable.
In an essay in the January Hastings Center Report, he elaborates on why this situation does not represent such an emergency, since the end does not justify the means when other reasonable strategies are available.
It's not just this decision that is at stake, opponents say. "Once you step off this cliff, you are in free fall," says Dr. Land. "If it's all right to kill babies to get tissue for research, then how do you say you can't create babies for the sole purpose of killing them?"