btw the discussion about polygamy serves as an excellent example of how Christians do and don't follow the Bible. Whatever your position on these matters of cultural relativity and inerrancy, this is a good example to explore. No one can doubt that:
Polygamy is practiced in the OT, and seems to have existed in NT times as well.
Polygamy is never prohibited. (And remember, this is a God who knows how to prohibit. The OT alone contains 613 commandments, and none of them against polygamy.)
Jesus did not condemn it.
The Bible does regulate polygamy.
Nevertheless, most modern Christians will assert that it is prohibited, and proceed to do what they call exegesis (or, if intellectual, hermeneutics) to show why it is NOT Biblical.
My understanding is that this was completely cultural. The ANE people did practice polygamy, and the Romans did not. When Christianity became the official Roman religion, Church leaders decided to go with the Roman, monogamous model, and decreed monogamy for Christians. It is not, however, required in the Bible.