Why is it that Christian people seem to think polygamy is worse than gay marriage?
The Bible gives no example of gay marriage and makes no comment about it. However, it does soundly condemn homosexual relationships. On the other hand, the Bible contains numerous examples of polygamy being practiced by faithful members of God's people. Nowhere do we find an outright condemnation or prohibition of the practice. Nowhere. Only two things I can think of argue against it: 1. Paul said that pastors (deacons, or whichever translation you want to use) should "be the husband of one wife." 2. Most of the polygamous relationships in the Bible led to problems, so the accounts of what happened can be taken to be advice against it.
Furthermore, there are cases where the OT law required polygamy. In certain situations, when a woman was widowed, her husband's brother was to marry her and raise children for his brother. It doesn't say "only if the brother is single" so this would lead to a polygamous relationship if the brother was already married.
I'm not defending legalization of polygamy, I just think we have the whole thing backwards. If polygamy is not good, then certainly gay marriage is far worse and shouldn't even be considered. Maybe our rallying cry should be "No gay marriage before polygamy."
Of course, the Netherlands case is a good example of moral problems all around. The married couple met a married woman in internet chat, got sexually involved with her, and as a result she got divorced and joined them. So the original couple here is guilty of marriage-busting, and of course, adultery. These three are obviously not going to be good poster children for polygamy.