The lawfulness of plural marriage,all the rules of a marriage contract, and divorce for a valid reason is all stated in the Quran. Likewise the forbiddance of adultery and that it is of the major sins is also in the Quran. So we Muslims accept all these as the speech and commands of God and not anything conjured up by mere mortals. And we as Muslims accept that God is All Knowing and has in His wisdom chosen certain things to be the way they are. This is all I can offer as an explanation and I suppose as a Non Muslim this might all seem hard to grasp but that's just the way it is.
The lawfulness of plural marriage,all the rules of a marriage contract, and divorce for a valid reason is all stated in the Quran. Likewise the forbiddance of adultery and that it is of the major sins is also in the Quran. So we Muslims accept all these as the speech and commands of God and not anything conjured up by mere mortals. And we as Muslims accept that God is All Knowing and has in His wisdom chosen certain things to be the way they are. This is all I can offer as an explanation and I suppose as a Non Muslim this might all seem hard to grasp but that's just the way it is.