“Of course, the moral revolution that has transformed marriage in our times did not start with the demand for legal same-sex marriage. It did not begin with homosexuality at all, but with the sexual libertinism that demanded (and achieved) a separation of marriage and sex, liberating sex from the confines of marriage. So sex was separated from marriage, and then sex was separated from the expectation of procreation and child-rearing. Marriage was separated from sex, sex was separated from reproduction, and the revolution was launched. Adding to the speed of this revolution, then, was the advent of no-fault divorce and the transformation of marriage into a tentative and often temporary contract.
“Once that damage had been done, the demand to legalize same-sex marriage could not be far behind. And now polygamy is enjoying its moment of legal liberation. Once marriage was redefined in function, it was easy to redefine it in terms of permanence. Once that was done, it was easy enough to redefine it in terms of gender. Now, with the logic of moral revolution transforming marriage in all respects, polygamy follows same-sex marriage. If marriage can be redefined in terms of gender, it can easily be redefined in terms of number.”
(Al Mohler, “Moral Mayhem Multiplied—Now, It’s Polygamy’s Turn”, AlbertMohler.com)