Re: the biblical definition of marriage
One of my friends posted the above picture on Facebook, which seeks both to demonstrate that the Bible does not exclusively present the monogamous 'one man, one woman' view and to criticize what the Bible does teach about marriage.
My response to this is that bogus exegesis abounds, and is easily refuted, if one actually cares what the text says, as I sought to demonstrate in a previous examination of Deuteronomy 22:28-29. Some of the other circumstances outlined in the above chart are similar to the situation in that passage; the woman is not being forced to marry, but the man-- who has acted unjustly-- is placed under legal/financial obligations to the one he has sinned against.
Furthermore, the examples (never commands) concerning polygamy/mistreatment of 'handmaidens'/ sexual misconduct with concubines, etc., are always accompanied with examples of the disastrous effects that come about due to such arrangements.
Finally, though this truth can certainly be distorted, it is definitely the case that the actions and teachings of Jesus bring greater clarity to the rest of Scripture. And Christ's instructions concerning marriage are crystal clear (see Matt 19:4-6).