Polygamy is indeed an interesting subject that comes up regularly at social gatherings.
The main arguments are
1. God created Adam and Eve: if he had intended Adam to have several wives, then he would have added a Doris, Jean and Mary, etc.
But at that time Adam and Eve were immortal and Adam was “innocent” and not “going in unto” Eve.
Matthew 19 says 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,
5 And said, For this cause shall a man leave father and mother, and shall cleave to his wife: and they twain shall be one flesh?
6 Wherefore they are no more twain, but one flesh. What therefore God hath joined together, let not man put asunder.
The feeling there is that there is a reference to only one wife, but there is not – it would apply to any one of any number of wives.
Matthew 22 saysM't:22:24: Saying, Master, Moses said, If a man die, having no children, his brother shall marry his wife, and raise up seed unto his brother.
M't:22:25: Now there were with us seven brethren: and the first, when he had married a wife, deceased, and, having no issue, left his wife unto his brother:
M't:22:26: Likewise the second also, and the third, unto the seventh.
M't:22:27: And last of all the woman died also.
M't:22:28: Therefore in the resurrection whose wife shall she be of the seven? for they all had her.
So we can see that the idea of supporting one’s brother’s possessions is firmly established in Christianity.
Unrelated women
The question of women who are
not previously owned is raised and answered as an aside in The Parable of the Foolish Virgins in Matthew 25:1-13 in which Jesus warns readers to be spiritually prepared: You will note that, throughout, the singular “bridegroom” and the plural “virgins” is used.
M't:25:1: Then shall the kingdom of heaven be likened unto ten virgins, which took their lamps, and went forth to meet the bridegroom.
Christ is silent upon the matter of one’s father’s wives (see Solomon and David in Sister Bassilia’s post above) – we can therefore assume that Christ accepted this idea naturally and without question.
The answer thus is that having multiple wives is perfectly natural but is, in itself either
(i) a social duty or
(ii) an opportunity to produce more soldiers for Christ if the current wife is already “with child” or
(iii) to the advantage of those who possess Christ-like stamina in the bedroom.
It should not be seen as an outlet for unbridled passion – that is why God made harlots (see
Ge:38:14 – 18) that those men who “have a sudden need to procreate” might find relief.
So having more than one wife is not, in itself, a sin if it is, for example, an act of charity but, outside this, it does seems to be somewhat of an immodest statement of having Christ-like powers in the bedroom area or the inability to pay a harlot, and thus should generally be avoided.