Just wondering what is particularly immoral about the principle and the practice of polygamy, and mind you it's not a form of slavery? The normal practice of po

Just wondering what is particularly immoral about the principle and the practice of polygamy, and mind you it's not a form of slavery? The normal practice of polygamy of single husband many wives has been practiced since the time immemorial and it's not condemned as immoral in all religious scriptures. For example Abraham as a great grandfather of Christian, Islam and Judaism religion is well known to have two wives with Ishak and Ismail are two sons from different wives. In fact I do believe that where polygamy are legally practiced the divorce rate is significantly lower but then I'm not the expert in sociology field. Don't get me wrong divorce is not immoral or sin, is just that it create a non-conducive upbringing environment for the children.