I am doing a debate and i was wondering can you tell me what are the bad things about stem cells?

Don't argue religion: The "bad thing" is that embryonic stem cells are taken from fertilized eggs created to help people have babies but not implanted. That's bad according to some religions, not science. Now that they are clearly going to be useful in treating at least one disease (wet macular degeneration), even the conservative candidate is suddenly not opposed to them. Your time's being wasted debating this stuff.

Stem cells not bad: Stem cells are not bad. These are there just like sun and earth. How you get them and what you do with them may be good or bad. Most people (not all) promoting stem cell treatment are charlatans. Check with your local medical school to ascertain if you may be a candidate for stem cell treatment.