Many churches teach that embryonic stem cell research is strictly wrong, while adult stem cell research is alright. What is the biblical basis for this teaching and why are the two distinguished?
This article gives a pretty good summary of the foundations, though I'm not going to endorse the argument it makes.
"Embryonic stem-cell studies are controversial because they involve the destruction of human embryos," the New York Times explained in a May 6 article reporting on the shifting politics of stem-cell research.
It's not complicated. An embryo used in stem-cell research (and fertility treatments) is three to five days past conception. It consists of a few dozen cells that together are too small to be seen without a microscope.
Those Christians who believe that life begins at the moment of conception, and that a cell cluster five days past conception is the equivalent of a human being, equate the use of embryonic stem cells with murder. Use of adult stem cells does not kill the donor.
There are other questions that address the biblical foundation for "life begins at conception".