1 Kings 11:1 But king Solomon loved many strange women, together with the daughter of Pharaoh, women of the Moabites, Ammonites, Edomites, Zidonians, and Hittites;
3 And he had seven hundred wives, princesses, and three hundred concubines: and his wives turned away his heart.
(The following is from answersingenesis.org by Roger Patterson)
Though our common usage of polygamy tends to be applied to a man with multiple wives, the word polygamy simply means multiple spouses. More accurately, polygyny would be one man with multiple wives, while polyandry would be one woman with multiple husbands. Bigamy is another word used for having two spouses. More recently, those who live in communities of open relationships have been called polyamorous, having multiple husbands, wives, boyfriends, and girlfriends in various arrangements. As we look at Scripture, none of these arrangements matches the structure of marriage given by God from the beginning.
Gen 2:18 And the Lord God said, It is not good that the man should be alone; I will make him an help meet for him. 19 And out of the ground the Lord God formed every beast of the field, and every fowl of the air; and brought them unto Adam to see what he would call them: and whatsoever Adam called every living creature, that was the name thereof. 20 And Adam gave names to all cattle, and to the fowl of the air, and to every beast of the field; but for Adam there was not found an help meet for him. 21 And the Lord God caused a deep sleep to fall upon Adam and he slept: and he took one of his ribs, and closed up the flesh instead thereof; 22 And the rib, which the Lord God had taken from man, made he a woman, and brought her unto the man. 23 And Adam said, This is now bone of my bones, and flesh of my flesh: she shall be called Woman, because she was taken out of Man. 24 Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh. 25 And they were both naked, the man and his wife, and were not ashamed.
Let’s look closely at this passage and note several key phrases that indicate God’s intent for marriage to be monogamous—one man for one woman. First, God intended to make “a helper” for Adam, not several helpers. Second, from one rib God made one woman for Adam. Genesis 2:24 reveals the pattern of a man leaving his family to “be joined to his wife,” not wives. This union is then described as becoming “one flesh.”
[The Law of First Mention for ‘marriage’ here teaches a monogamous marriage between two consenting adults of opposite genders.]
Jesus confirmed this understanding of marriage when he was asked about divorce by the Pharisees.
Matt 19:4 And he answered and said unto them, Have ye not read, that he which made them at the beginning made them male and female,
In His response Jesus quoted from Genesis 2, confirming that His understanding of marriage was one man for one woman. Confirming the covenantal nature of marriage, Jesus said that divorce was only allowed because of the hardness of the hearts of man. God intended, from the beginning, for marriages to consist of one man and one woman for the duration of their lives. Divorce and polygamy were regulated in the laws given to Moses, but polygamy was recorded long before then. [It was one male and one female to be married; this was designed by God from the ‘beginning’.]
Following from this God-established example, this was the general practice until interrupted by sin.
Gen 4:1 And Adam knew Eve his wife; and she conceived, and bare Cain, and said, I have gotten a man from the Lord.
The first recorded polygamist, Lamech, was a wicked man [(a murderer)].
Gen 4:23 And Lamech said unto his wives, Adah and Zillah, Hear my voice; ye wives of Lamech, hearken unto my speech: for I have slain a man to my wounding, and a young man to my hurt.
(Norman L. Geisler)
[The Law of First Mention teaches here that polygamy was associated with rebellion.]
It is interesting to note that there are no passages in Scripture that clearly state [that polygamy is wrong.] However, polygamous relationships are never mentioned in a positive light, and, indeed, the problems of such relationships are presented.
Consider the consequences [of polygamy] revealed in Scripture in each of the following cases: Abraham—led to bitterness between Sarah and her maid, Hagar, and the eventual dismissal of Hagar and Ishmael; Jacob—led to Rachel’s jealousy of Leah and to Joseph being betrayed and sold by his half-brothers; David—led to the rape of one of his daughters (Tamar) by one of his sons (Tamar’s half-brother Amnon) and Amnon’s subsequent murder by Tamar’s brother Absalom; Solomon—his many wives “turned away his heart” from the Lord and to the worship of false gods (1 Kings 11:1–8). Just because the Bible records polygamous relationships does not mean that God approves of such things.
[The Law of Moses prohibited polygamy [(at least with kings)].
Deut 17:17 Neither shall he multiply wives to himself, that his heart turn not away: neither shall he greatly multiply to himself silver and gold.]
Other religions have promoted polygamy. For example, according to Sura 4:3 of the Koran, Islamic men are allowed to take up to four wives under certain circumstances. Muhammad was granted the privilege of many wives in Sura 33 and had many wives. Modern Muslims practice polygamy in various ways according to their cultural context. Historically, members of the Latter-day Saints (LDS or Mormons) practiced polygamy, although the acceptance of the practice changed as new “revelation” was given to the prophets of the church. Initially, the Book of Mormon decried polygamy. Jacob 2:23–28 and 3:5–8 denounce the practice of polygamy as an abomination before God. Likewise, the Doctrine and Covenants (a supposed revelation given to Joseph Smith) state clearly that marriage should be one man for one woman (D&C 42:22). Later writings of Smith allow for 
unlimited plural marriage to virgins (D&C 132:51–66) and directly contradict what had been written earlier.
Polygamy, more accurately polygyny, was practiced secretly by some Latter-day Saints from the 1830s until the 1850s, when the church admitted to the teaching after many previous denials. Eventually, they were pressured into denouncing polygamy after it was vigorously prosecuted by the federal government. From the 1870s on, many LDS leaders encouraged rebellion against the laws, but in 1890, LDS president Wilford Woodruff encouraged members to obey the laws. This caused a large split in the church, and new organizations were formed [(the largest being FLDS)] by those who continued the practice of polygamy and considered themselves as faithfully adhering to the commands of God over man’s laws. Some secretly practiced polygamy while others abstained. What has become the mainline LDS Church currently denounces polygamy and claims that anyone who practices it is not a true Mormon. It is clear that, despite appeals to the patriarchs, the Bible was not the source of the Mormon doctrine of polygamy.
With the current tide of the redefinition of marriage, polygamous marriages may be legal in the near future. Once that prohibition is removed, it will be interesting to see how the members of the LDS Church respond.
Despite these supposed additional revelations from God, the Bible makes it clear that He intends marriage to be between one man and one woman—as it was “from the beginning” (Matthew 19:8; Mark 10:6). Any challenge to this teaching stands in opposition to God’s plan for His creation.
(The following is taken from Slate.com’s article by Jillian Keenan – a feminist)
Recently, Tony Perkins of the Family Research Council reintroduced a tired refrain: Legalized gay marriage could lead to other legal forms of marriage disaster, such as polygamy. Rick Santorum, Bill O’Reilly, and other social conservatives have made similar claims. It’s hardly a new prediction—we’ve been hearing it for years. Gay marriage is a slippery slope! A gateway drug! If we legalize it, then what’s next? Legalized polygamy?
Legalized polygamy in the United States is the constitutional, feminist, and sex-positive choice. More importantly, it would actually help protect, empower, and strengthen women, children, and families.
Right now, all polygamous families, including the healthy, responsible ones, are driven into hiding (notwithstanding the openly polygamous Brown family on TLC’s Sister Wives, that is). In the resulting isolation, crime and abuse can flourish unimpeded.
It’s also hard to argue with the constitutional freedom of religious expression that legalized polygamy would preserve. Most polygamous families aremotivated by religious faith, such as fundamentalist Mormonism or Islam, and as long as all parties involved are adults, legally able to sign marriage contracts, there is no constitutional reason why they shouldn’t be able to express that faith in their marriages.
We have a tendency to dismiss or marginalize people we don’t understand. We see women in polygamous marriages and assume they are victims. “They grew up in an unhealthy environment,” we say. “They didn’t really choose polygamy; they were just born into it.” Without question, that is sometimes true. But it’s also true of many (too many) monogamous marriages. Plenty of women, polygamous or otherwise, are born into unhealthy environments that they repeat later in life. There’s no difference. All marriages deserve access to the support and resources they need to build happy, healthy lives, regardless of how many partners are involved.
“Monogamy is God’s ideal standard for the human race. Polygamy was never commanded by God; it was only tolerated. Polygamy was never established by God for any people under any circumstances.
Though the Bible records instances of polygamy, this does not mean God approved of it. Monogamy is taught in the Bible by precedent: since God gave the first man only one wife; by the equal proportion of males and females God brings into the world; by precept of Old and New Testament commands; and by punishment, since God punished those who violated his standard (1 Kings 11:2).” (Norman Geisler)