The gist of it is this: In promoting ESCR as the means to cure every disease, its proponents fail to mention where they will get the embryonic stem cells in which they place so much hope. Simple logic tells us that embryonic stem cell research requires ... embryos -- lots of them. And the way you get lots of embryos is to mass-produce them. This requires lots of eggs from women who get paid to donate them. It also requires that those eggs become fertilized to form the embryos needed to do the research.
The best, most efficient way to produce lots of embryos then, is to create them by removing the egg cell nucleus (which only contains half the DNA needed for a fully formed embryo) and replacing it with a complete set of DNA from the nucleus of a body (somatic) cell -- that is, to insert the somatic cell nucleus into the the de-nucleated egg cell. The scientific term for this procedure is perfectly descriptive of the process -- somatic cell nuclear transfer (SCNT). You may not recognize this term but I can promise you that you have heard it talked about in another way. It is also known as cloning.
Because cloning has such an eerie, science-fiction sound to it, its proponents either avoid using the word altogether or stick softening adjectives in front of it to make it sound more acceptable. So we are conditioned to differentiate between reproductive cloning and therapeutic cloning, the former being the (so far) unacceptable option that conjures images of a horror film, while the latter offers hope for curing all disease. "It's therapeutic, isn't that cool?"
Here's the thing. There is absolutely no difference in the process that leads to reproductive or therapeutic cloning. They are the same thing. The only difference between the two is in the future of the embryos created by that process. And here we expose the most bizarre immorality of the whole thing: Reproductive cloning is illegal. Therapeutic cloning is just fine. In other words ...
If you artificially create human embryos with the intention of allowing them to live, you will be prohibited from doing so.
But ...If you artificially create human embryos with the intention of destroying them by tearing them apart to do research, go right ahead.
Don't buy the rhetoric. Remember what the embryo is -- an unborn, unique human person. ESCR is morally repugnant for the same reason abortion is -- it destroys that person. And "therapeutic" cloning is an oxymoron -- especially if you happen to be the embryo whose cells provide the desired "therapy."