A good manifesto about the call is from Robert P. George's NRO article "Families and First Principles," available in full only to digital or hard-copy subscribers. So I rely on Vivificat for the most pertinent passage:
Our task should be to understand the moral truth and speak it in season and out of season. We will be told by the pure pragmatists that the public is too far gone in moral relativism or even moral delinquency to be reached by a moral argument. We will be advised to make the moral arguments to the social-conservative "base" but to frame those arguments in coded language so as not scare off the soccer moms or whoever is playing their role in the next election cycle. All of this must be resisted.
We must, to be sure, practice the much-neglected and badly underrated virtue of prudence. But we must have faith that truth is luminously powerful: so that if we bear witness to the truth about, say marriage and the sanctity of human life—lovingly, civilly, but with passion and determination—and if we honor the truth in advancing our positions, then even many of our fellow citizen who now find themselves on the other side of these issues will—some sooner, some later—come around.
To speak of truth frightens many people today. At least they seem to be frightened when conservatives speak of truth. They evidently believe that people who claim to know the truth about anything—and especially about moral matters—are "fundamentalists" and potential totalitarians. But this is silly. As Hardley Arkes has patiently explained in the pages of NATIONAL REVIEW and elsewhere, those on the other side of the great debates over social issues such as abortion and marriage make truth claims—moral truth claims—all the time. They assert their positions with no less confidence and no more doubt than one finds in the advocacy of pro-lifers and defenders of conjugal marriage. They proclaim a woman's "fundamental right" to abortion. They insist with moral conviction that "love makes a family." They condemn "Bush's immoral war in Iraq." The question is not whether there are truths about the morality of abortion and the nature of marriage; the question in each case is: What is the truth?
That last question is not to be asked with the relativistic cynicism of Pontius Pilate, so common today. It is to be asked with the expectation that we have already been given enough of the answer to act upon. This Lent, let us empty ourselves of worldliness so as to be filled with the courage and hope to act accordingly.