How do you respond to people who use your own language against you in this way:
"Marriage already HAS been redefined. Polygamy was once the norm... acceptable to God, now it's taboo. Gay marriage is no more a violation of natural law than that was."
There are many things wrong with the quote. And I am equally as frustrated with such arguments from people because they ignore basic concepts that we all utilize.
Here are the top 5 assumptions made by this quote...
1. "God changed the definition of marriage, so we can too."
2. "When things are changed once, this means that there really is no definition at all and it can therefore be changed numerous times."
3. "Polygamy was the norm." This is simply a false statement. I am not aware of polygamy being a norm... at least among common folk. Certainly it was practiced among that wealthy and politically influential, but I am not too sure about it being a "norm".
4. "Acceptable" is a tricky word. There are some things that are acceptable because they are necessary, and there are some things that are acceptably because they are ideal. I'm not too sure that God found polygamy ideal even if it was acceptable given the circumstances of the people He was dealing with.
5. "Polygamy is taboo." Not it isn't. It is simply impossible. At least for the baptized. Marriage was restricted to a monogamous relationship after Christ established the Sacrament. This doesn't make the former taboo, it simply makes it impossible. A restriction is not a change in substantial meaning. A man still may marry a woman. But, it stops there. In polygamy, he could repeat that process. But, there isn't a change in substance here. In both monogamy and polygamy there was a man marrying a woman. So, the comparison here is untenable. With polygamy to monogamy we are dealing with a restriction of how many times the action can be repeated. With heterosexual to homosexual we are dealing not with repetition, but with substantial change in meaning.
I could go on, but that is enough...
As to number 1, it is clearly false. If God changes something it is always to make it better. Before Sacramental marriage, there was only natural marriage. All that is being claimed here is that polygamy is allowed under Natural Law, but not under Sacramental Law. So, there is nothing to compare to gay marriage here.
As to number 2, I think that speaks for itself. We are not God. If God wants to change something (as he clearly did in the institution of marriage) it does not mean that we can then do the same. We restrict marriage to one because of a clear command of Christ. That is the authority. There is nothing about gay marriage. We cannot argue that "Christ changed it so we can as well."
As to number 3, I would simply like to see the evidence of that.
And I already responded to 4 and 5.
This explanation is clearer to me. Thank you.