God never condoned polygamy but like divorce he allowed it to occur and did not bring an immediate punishment for this disobedience.
Deuteronomy. 17:14-17 “I will set a king over me like all the nations that are around me,' “you shall surely set a king over you whom the LORD your God chooses; one from among your brethren you shall set as king over you; you may not set a foreigner over you, who is not your brother. But he shall not multiply horses for himself, nor cause the people to return to Egypt to multiply horses, for the LORD has said to you, 'You shall not return that way again.' “Neither shall he multiply wives for himself, lest his heart turn away; nor shall he greatly multiply silver and gold for himself.” This is the command of God, and he has never changed it.’
Was Abraham, David Solomon condemned or approved for practicing polygamy? Well they certainly did not get blessed for it! In fact every polygamist in the Bible like David and Solomon (1 Chron. 14:3) were punished. This should be evidence that this is not God’s will. Scripture has always commanded monogamy (Ps.128:3; Prov. 5:18; 18:22; 19:14; 31:10-29; Eccl. 9:9).
Deuteronomy. 17:14-17 “I will set a king over me like all the nations that are around me,' “you shall surely set a king over you whom the LORD your God chooses; one from among your brethren you shall set as king over you; you may not set a foreigner over you, who is not your brother. But he shall not multiply horses for himself, nor cause the people to return to Egypt to multiply horses, for the LORD has said to you, 'You shall not return that way again.' “Neither shall he multiply wives for himself, lest his heart turn away; nor shall he greatly multiply silver and gold for himself.” This is the command of God, and he has never changed it.’
Was Abraham, David Solomon condemned or approved for practicing polygamy? Well they certainly did not get blessed for it! In fact every polygamist in the Bible like David and Solomon (1 Chron. 14:3) were punished. This should be evidence that this is not God’s will. Scripture has always commanded monogamy (Ps.128:3; Prov. 5:18; 18:22; 19:14; 31:10-29; Eccl. 9:9).
Abraham married his half sister, at the time it was allowed . . then in Leviticus 18:9 God commands "The nakedness of thy sister, the daughter of thy father, or daughter of thy mother, whether she be born at home, or born abroad, even their nakedness thou shalt not uncover." [NIV-Do not have sexual relations with your sister, either your father's daughter or your mother's daughter; that would dishonor you.] - that has not changed. The point is at one time it was allowed.
Jacob married sisters, Rachal and Leah, at the time allowed . . . then in Leviticus 18:18 Neither shall thou take a wife to her sister, to vex her, to uncover her nakedness, beside the other in her life time. [NIV Do not take you wife's sister as a rival wife and have sexual relations with her while your wife is living.] - that has not changed. The point is at one time it was allowed.
I don't believe you are following what I am saying . . . where sometimes some things were allowed, God changed the rules and made them un-allowable (good word just not sure if it is a word!!!) and then some things that were at one time un-allowable are now allowed.