Authors of What is Marriage? One Man, One Woman: A Defense (which you can purchase here) write in the most recent print edition of National Review:

In our new book What Is Marriage? Man and Woman: A Defense, we make a rational case for the historic understanding of marriage as a conjugal relationship — a union of a man and a woman at every level (mind, heart, andbody), inherently oriented to family life. We show how the common good depends on enshrining this view in law, and answer all the most significant criticisms of this view (having to do with equality, freedom, neutrality, interracial marriage, infertile couples, and much more). We show how the argument for redefining marriage contradicts itself, and document the many ways that embracing it would harm the common good. And we show how society can support marriage without ignoring the needs, undermining the dignity, or curbing the fulfillment of people with same-sex attractions.

Here, we respond to some challenges that even those sympathetic to our views might raise: Why worry about same-sex marriage in particular? Why worry about marriage policy? If marriage policy does matter, why not “broaden the definition” of marriage to promote family values? How would recognizing same-sex relationships as marriages harm marriage? Isn’t ours a losing cause, or at best a secondary one? And why privilege anyone’s sectarian values at all — doesn’t that compromise freedom and equality? We address each of these questions in turn.