Interesting article http://thegospelcoalition.org/article/s ... ex-wedding, specifically because of this paragraph:
"Biblically and historically we can see a number of examples where marriages are in some measure wrong but remain legitimate. For example, consider the case of polygamy, which falls short of God’s intention for marriage to be "one man, one woman" (Matt 19:5) and bars a man from eldership in the church (1 Tim 3:2), but which the Bible doesn’t condemn as illegitimate marriage."
I scanned the comments and didn't see any significant naysayers on polygyny. Most of them seem to be agreeing that it's not ideal but it's not sin.
"Biblically and historically we can see a number of examples where marriages are in some measure wrong but remain legitimate. For example, consider the case of polygamy, which falls short of God’s intention for marriage to be "one man, one woman" (Matt 19:5) and bars a man from eldership in the church (1 Tim 3:2), but which the Bible doesn’t condemn as illegitimate marriage."
I scanned the comments and didn't see any significant naysayers on polygyny. Most of them seem to be agreeing that it's not ideal but it's not sin.