You have to understand that the Bible is really a library of books and it has different categories of material. There are certain parts which you have to say no to. The Bible accepted slavery. St Paul said women should not speak in church at all and there are people who have used that to say women should not be ordained. There are many things that you shouldn't accept.
You will find that the Bible, if you want it to, will justify many things. St. Paul had a very male chauvinistic view of women. He would say things like women must not talk in church, must cover their heads, they mustn't talk and must remember that it was a woman who first tempted and this whole mess started because women messed us up. So you can read it in such a way that it justifies polygamy.
