"Why are evangelicals so concerned about AIDS in Africa and sex trafficking and slavery in Sudan? I thought all you cared about was abortion and gay rights."

The reporter from a prestigious journal had been following the Bush administration's foreign policy initiatives and stumbled onto a curious fact: Evangelicals were behind most of them.

The reporter's question gave me a wonderful opportunity to explain that evangelicals believe in the sanctity and dignity of all human life—not just unborn children, but also Sudanese slaves, sex trafficking victims, and Africans with AIDS.

The reporter got it; her subsequent front-page story contained unusual praise for evangelicals. This experience offers an insight on how we can make a powerful witness.

Over the past few years, evangelicals have actively promoted a morally grounded foreign policy. Six years ago, when no one was talking about the horror of sex trafficking, conservative activist Bill Bennett and I—prodded by the indefatigable human rights champion Michael Horowitz—helped organize a coalition to fight this evil. We testified to Congress in opposition to the Clinton administration, which had caved in to radical feminists who argued that prostitution should be redefined as "sex work"—just another empowering career option, like nursing or teaching.

Because of the leadership of Christians like Frank Wolf, Chris Smith, Joe Pitts, and others in Congress, legislation passed in 2000 authorizing sanctions. When the Bush administration took over, it appointed an "abolitionist"—gutsy former Congressman John Miller—to lead the trafficking office.

During his speech to the United Nations last year, President Bush powerfully decried the "special evil" of sex trafficking. The reporter interviewing ...