There are some countries/cultures where polygamy is legal. However it is not so in the U.S.A.
With regard to the Christian faith there are several recorded instances of men having many wives and concubines. According to the bible;
(King Solomon had 700 wives and three hundred concubines!) King David also had multiple wives as well.
In fact (2 Samuel 12:8) states something along the following with regard to David;
"And I gave you your master's house, and your master's (wives) into your bosom, and gave you the house of Israel and of Judah; and (if that had been too little, I would moreover have given unto you more things..)"
Another verse (Exodus 21 :10) states the following;
"If he take him another wife; her food, her raiment, and her duty of marriage, shall he not diminish." This would imply that as long as the man could afford it as well as make himself "available equally" then it was ok to have multiple wives. Mind you this is all (Old testament) stuff.
No matter what was said or written in the past one has to follow the laws of the country they reside in.