Q. What about 1st Corithians 7:39? Paul is talking in the singular, i.e., wife.
This passage of scripture has nothing to do with monogamy or polygamy but is describing the marriage estate in general. Thus if I were to say, "A son should obey his father in righteousness", this would not mean that the father had only one son, or that the father was not allowed to have more than one son. For the statement made by Paul to be referring to a solely monogamous practice it would have to be worded in a completely different way. The passage in question is, in any case, to be seen in its original context of Paul's advice to widows and the unmarried in a rather special situation, viz. the wayward and immoral Corinthian saints.
"A wife is bound to her husband as long as he lives. If the husband dies, she is free to be married to whom she wishes, only in the Master" (1 Corinthians 7:39, RSV)
A better passage in support of monogamy might be at the beginning of the chapter:
Yet here also the monogamist faces a similar problem for this passage does not exclude polygamy. It must always be remembered, moreover, that monogamy is the first stage of polygamy -- all polygamous marriages start as monogamous ones. It is the minimum condition of marriage - to be married, a woman must have a husband, and a man must have a wife. In polygamy, a woman must have a husband, and a man must have at least two wives...and so on.
"But because of the temptation to immorality, each man should have his own wife and each woman her own husband" (1 Corinthians 7:2, RSV).
To be a car-owner, a man must have at least one car, and a car must have at least one owner (feminists: don't go and make too literal comparsions with this analogy, please - I'm not saying polygamous men are car salesmen!). But a car-owner may have two cars (as indeed many do). The point I am making is the minimum condition. To pay income tax I must have at least one job but this does not prevent me from having more than one job. However, that job is solely mine, and somebody else cannot have that job too.
When you discuss car ownership and how to take care of a car, you normally assume there is only one car, though this does not exclude ownership of two or more cars. Paul is discussing the marriage condition, not how many wives a man may have. There are, to my knowledge, only three places in the New Testament were polygamy is mentioned, albeit indirectly - two concern the relationship of Pastors and Deacons to their first wives, admonishing them to be faithful to their first sweethearts should they take more wives (Titus 1:6 and 1 Timothy 3:2,12), and the third addresses a problem in the Corinthian congregation (again!) where a son has fornicated with one of his father's wives (1 Corinthians 5:1) - for a more detailed examination of these passages, see What the New Testament Says About Polygamy .
The passages sited by anti-polygamists from the Bible are almost always about the general practice of marriage and have nothing to do with the issue of monogamy or polygamy. They totally ignore the many passages that sanction polygamy or bother to consider the consequences of their anti-polygamous position, namely that to attack polygamy is to accuse Yahweh of being a liberal, permissive adulterer who chops and changes His position when it suits Him. There is, quite simply, no defence for the anti-polyagmist if he claims to be a Bible-believing Christian/Messianic. For in order to defend his position, he must ultimately - if he takes his position to its logical conclusion - reject the Bible and the Elohim (God) of the Bible and be numbered with the unbelievers who are bound for an eternity without Elohim (God).