Calling this a powerful defense for same sex marriage is a joke. In fact, it's based on a premise that is patently false.
Several websites have discussed the fact that this politician simply doesn't understand the Bible. This one
gives a pretty good synopsis of exactly why he was wrong.
Here's another site
which explains - in detail while citing the Bible itself - why the idea that the Bible condones slavery is a misunderstanding. Perhaps this politician should have read that information before he made his comments.
No, BL, the U.S. does NOT need more politicians who blurt out incorrect statements so that crowds of ignorant people can applaud because it forwards their ridiculous agenda.
In fact, it's a good thing for Australia the polls indicate this guy is going to lose in the election.