I have been surprized that no one has made any attempt to demonstrate that Polygamy is a sin under the New Covenant. There is no question that Christ changed the rules concerning divorce. The "for uncleaness" ground has been replaced with "adultery only." It is assumed by most writers that Matthew 19, by implication, includes condemning Polygamy. John  Murray is an example

I was curious and looked up Polygamy on the Net and was amazed at the polemics defending Polygamy todayby not only Mormans but some professed evangelicals!. There are many advertisements looking for women to become the fourth, fifth and even higher wife in a Polygamous home. There are also detailed ways of legally practicing Polygamy today.

Exactly how would you biblically use the New Testament Scriptures to condemn Polygamy today. I would appreciate any input. I am fully convinced the New Covenant Scritures condemn Polygamy beyond question. However, I may have missed some arguments and I don't like loose ends unless they are unavoidable..

JGR