A common misunderstanding of the Bible consists of questioning why the authors seem to accept actions which are clearly morally wrong. The Bible often talks of slavery, adultery, polygamy, and a host of other sins that by today’s standards are clearly morally wrong.
This is one of the dangers of looking at the Bible as a guidebook for moral living. It was not written as a guide for moral living, but as a story of how God shows grace in the midst of a depraved world. It is not about teaching us how to be a better person, but a story of both how God shows us grace in spite of mankind’s failure to be morally upright, and how we as receivers of His grace are to respond.
An excellent example is Onesimus in Paul’s letter to Philemon. Onesimus ran away from Philemon, and apparently stole from Philemon. Paul at no point supports or condemns the sins of slavery. Instead He encourages Onesimus to return to Philemon. He encourages Philemon to forgive Onesimus as a brother in Christ. This letter does nothing to encourage or condemn slavery, rather it is a beautiful picture of how two brothers in Christ are to respond to each other in grace in the morally wrong culture which supported slavery.
The story of Abraham in the Old Testament is similar. Abraham clearly engaged in polygamy. At no point does the author support or condemn polygamy. Instead, he gives a wonderful picture of God showing grace and keeping His covenant in spite of Abraham’s sins.
Nothing has changed in our society. We live in a society that, for reasons ranging from economic problems to adultery to substance abuse issues to mental health issues, has placed many people in family relationships that do not conform to our ideal of a “normal” family. The false church in Western society has placed great emphasis on promoting the ideal family, and the Christian bookstores are full of books on being a better family member. However, I have seen no example of how the saints of old ever promoted the ideal family. Rather, they documented how God shows grace and keeps his covenant, regardless of the circumstances of society or our life.