I would have thought that a man from Utah would have asked me this question and here you are a woman from Miami.
There are several places in the New Testament that teach that a man can only have one wife. Let's start with the book of Matthew.
1.Jesus taught against plural marriages Matthew 19:4-9
"Haven't you read," he replied, "that at the beginning the Creator 'made them male and female,'[a] 5) and said, 'For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh' 6) So they are no longer two, but one. Therefore what God has joined together, let man not separate."
7) "Why then," they asked, "did Moses command that a man give his wife a certificate of divorce and send her away?"
8) Jesus replied, "Moses permitted you to divorce your wives because your hearts were hard. But it was not this way from the beginning. 9) I tell you that anyone who divorces his wife, except for marital unfaithfulness, and marries another woman commits adultery"
a. The first point to notice is that the two become one flesh (V. 5-6)
b. The second point is found in (v.9) and it tells us that if a man does marry another woman this second relationship is considered to be an adulterous one not a marriage.
Only two conditions are given for a second marriage to be accepted as a legitimate marriage in GOD'S eyes and that is if the first one was ended for reasons of adultery or death.
2. Plural marriages are forbidden for Church leadership (1 Timothy 3:2+12)
Both Deacons and Elders can have only one wife.
a. Elders (overseer)
"Now the overseer must be above reproach, the husband of but one wife."
" A deacon must be the husband of but one wife...."
The logical thought may have entered your mind at this time that if elders and deacons are told to have only one wife then it may be OK for those who were neither a deacon or an elder.
The answer to that is at that time in history it was common for many people to have several wives. Once they were converted it would be unfair and destructive to
break up that family structure in that it would place a hardship on the wives and children of these wives.
But this does not mean that plural marriages were sanctioned by the church. Especially when Jesus said not to do it. So these marriages were permitted to "play out" with future plural marriages not permitted. Deacons and elders set the pattern for marriage of one man and one woman.
3. Marriage is seen to be a one man and one woman relationship
Notice the wording found in (1 Corinthians 7:2) regarding the exclusive relationship
between a man and a woman in marriage. In particular notice the words "his own wife" and "her own husband". He would not be referred to as "her own" if he was shared with others.
" ...each man should have his own wife, and each woman her own husband"
Carmen, this was a good question you asked . The answer is clearly spelled out for us. Plural marriages are not allowed for Christians.