The lone bright spot last week was the release of Ryan Anderson's much-anticipated (by me, at least) book on Obergefell and the future of marriage. It's called Truth Overruled: The future of marriage and religious freedom and I cannot recommend it highly enough.

Anderson has pulled of a great trick with Truth Overruled: He's written a book that should be of interest not just to proponents of traditional marriage, but to the people who have advocated for redefining marriage, too. That's because what he does is distill, in an even-handed and philosophical manner, exactly what the arguments are for traditional marriage and what the costs to society are likely to be from redefinition.

Truth Overruled is so pithy and lean that I could quote the entire thing back at you. But I want to focus on two of Anderson's larger points.

The first is that when it comes to marriage, you can either have the traditional standard, or no standards, for defining the institution.

Marriage is, as Anderson explains, a human institution which predates the state. Why did it form? In order to make men and women responsible to one another, and to maximize the outcomes for both the adults and any children which result from their union. As such, "Marriage is society's least-restrictive means of ensuring the well-being of children."

The people who want to transform marriage to include same-sex relationships have, whether they know it or not, not just a practical goal, but a philosophical one, too: They want, as Anderson puts it, to turn marriage into "an instrument for gratifying the emotions of adults." (This is not, I think, a redefinition that most same-sex marriage proponents would object to.)

The problem is that when you shift the institution's purpose, you then change the institution. And this isn't the first time we've confronted this movement. Here's Anderson:

The same argument was made during the no-fault divorce debate. No-fault divorce was for the relatively small number of people suffering in unhappy marriages and would be irrelevant for everyone else. But the change in the law changed everyone's expectations of marital permanence. The breakdown of the marriage culture that followed made it possible in our generation to consider removing sexual complementarity from the legal definition of marriage. And that redefinition may lead to further redefinition.

In short: Once you move away from the original purpose and definition of marriage, you enter a world in which the institution is infinitely plastic. Which means that if you support same-sex marriage today, you need to be comfortable with whatever marriage will be defined as tomorrow. And there will be future redefinitions.

Furthermore, you need to be comfortable with the trade-offs you're making.

What people often fail to understand is that rights are in constant tension with one another. Expanding one set of "rights" and "freedoms" comes with a cost. Anderson sees four them, right off the top:

Law teaches. It shapes ideas, which shape what people do. A radical change in the law of marriage will have at least four harmful consequences that we can foresee. The needs and rights of children will be subordinated to the desires of adults. The marital norms of monogamy, exclusivity, and permanence will be weakened. Unborn children will be put at even more risk than they already are. And religious liberty-Americans' "first freedom"-will be threatened.

It's this last threat-to religious freedom-which occupies a great deal of thought in Truth Overruled, because it is the most immediate consequence of the Supreme Court's Obergefell decision.

With marriage now redefined, we can expect to see the marginalization of those with traditional views and the erosion of religious liberty. The law and culture will seek to eradicate such views through economic, social, and legal pressure. With marriage redefined, believing what virtually every human society once believed about marriage will increasingly be deemed a malicious prejudice to be driven to the margins of culture.

And you can see this even with Anderson's book itself. Within hours of it going on sale, gay-marriage activists swarmed the site and deluged it with negative reviews. Most of the reviewers made no pretense of having read the book. And when the Daily Signal investigated the situation, they found that gay-marriage activists were coordinating not just to leave negative reviews on Amazon-and reviews which were frequently nasty and personally vindictive-but to down-vote any positive reviews from people who had actually purchased and read the book.

These are the tactics of the gay-marriage movement. They want not just a redefinition of marriage-which they've gotten, courtesy of a single justice on the Supreme Court-but the total extirpation from the public square of anyone who holds to the view of marriage which was unquestioned for thousands of years of human history.

And they will pursue this goal by any means necessary. Ryan Anderson's Truth Overruled is the first step toward pushing back against these Jacobins.