Let me start by saying that I mostly agree with your points, and am intending to further discussion rather than bash you. It's always hard to tell on the Internet.
really care about banning gay marriage
I care about retaining the meaning of the word marriage.
Why? This is something I hear a lot in the gay marriage debate but have never really understood. Obviously, you can't speak for all people who hold this view, but I'd like to try to understand this sentiment better.
For the purpose of comparison, my position on this is that I care about the meaning of the word "marriage" only insofar as it is an English word which allows for unambiguous communication. I care as much about the meaning of the word "marriage" as I do about the word "house" or "fire." In other words, it would be a shame if the word "marriage" had to be substituted for a much longer explanation in order to accurately convey a particular meaning. As a specific cultural institution, I don't really care about preserving it.
So my question is, "what do you mean by 'retaining the meaning of the word marriage' and why is that important?" I genuinely don't understand this sentiment and would like to try to understand it better.
I really could care less about gays living together, and quite honestly I think that the tax/medical/whatever benefits available to married couples should be extended to any two cohabitating people. [...]
We seem to be in perfect agreement about this. I might go further and remove the words "two" and "cohabitating," but I'm still thinking about that one.
Ah, the concept that a human isn't human because it's still in inside its mother.
This is an issue which I doubt will ever really be "fully" resolved, since it is so subjective. Does human life begin at conception? Does it begin at the act unprotected sex? When the sperm and egg plasma membranes fuse? When the haploid egg and sperm cells fuse to create a diploid zygote? When the heart starts beating, or when a certain amount of brain function is achieved? Is it at birth, or when the baby begins to respirate, or when it can see? Are sperm and egg cells alive? (well, yes) When are they considered human? Is it wrong to allow an egg to go unfertilized?
There is no real answer to these questions, since they all depend on such subjective opinions of what constitutes a human or "potential human." Since it will always be arbitrary, we choose an arbitrary point at which to make the cutoff, birth being an unambiguous one. The problem I have with moving the cutoff earlier (and especially within the first trimester) is that it then include morning-after pills and intrauterine devices, since they act after fertilization, but prevent implantation (well, for morning-after pills, it seems like the research isn't completely settled on that point). Are we allowed to induce medical abortions through drugs like Mifepristone? It's a sticky subject.
Tell me, are there other places a human can be where they aren't human? Maybe we could re-define Gitmo as a womb, from a legal standpoint, so that the prisoners held there don't have to be treated humanely.
I think you have to be careful with slippery-slope arguments, since they can often be used to argue for or against any position. Obviously, any legislation about whether someone is "legally a human" should be extremely specific and inflexible, so that problems such as "defining Gitmo to be a womb" are as hard as possible.
Same old FUD. I must admit, I'm not surprised. I'm not against stem cell research. I'm against killing unborn children to harvest their stem cells, but first of all that isn't necessary and secondly those stem cells have been spectacularly ineffective anyway.
I'm against killing unborn children to harvest their stem cells as well, but I don't see a problem with harvesting the stem cells of an already-aborted fetus. The tricky part is that one could argue that allowing the use of fetal stem cells would incite abortions if it was financially beneficial to the woman considering the abortion. I sympathize with this view, but I feel like it is, by itself, unlikely to have any meaningful effect on abortion rates. In other words, I am opposed to fetal stem cell research only insofar as it encourages unnecessary abortions, or those which would not otherwise have happened.
Simply, fetal stem cell research is fine, inciting abortions to increase the supply of fetal stem cells is not.