Stand to Reason has published a list of "talking points" that can be used as a quick reference sheet for answering questions about embryonic stem cell research and why people ought to oppose this procedure. The piece, entitled "Are you against stem cell research and cloning?" give good, concise answers to some of the questions that arise concerning why Christians would oppose this procedure when it supposedly holds such great promise.
For example, consider the following from the "talking points":
Where do we get human embryonic stem cells? We can only derive human embryonic stem cells by killing a human embryo. Removing its stem cells leaves it with no cells from which to build the organs of its body.
What is the embryo? An embryo is a living, whole, human organism (a human being) in the embryonic stage. All the embryo needs to live is a proper environment and adequate nutrition, the very same thing all infants, toddlers, adolescents, and adults need.
This is a key concept in this debate -- the only way to get usable human embryonic stem cells is to kill the embryo. The embryo is simply a human being in an early stage of development. Thus, taking the embryo kills a human being. This is not particularly debateable.
If you are interested in this issue so involved in the culture of life, you should take a few moments to review this short (two-page) article. It is very helpful.