Rep. Frank Wolf insists that words matter. In “Prisoner of Conscience: One Man’s Crusade for Global Human and Religious Rights,” the Virginia Republican recounts instances in which words sometimes failed and sometimes made a difference.

But in either case, he kept on talking.

“The words of the Constitution are a covenant with the entire world,” Wolf said in a phone interview, paraphrasing President Ronald Reagan. “We have a moral obligation to speak.”

The co-author of “Prisoner of Conscience” is Anne Morse, who worked on Charles Colson’s radio show for years. She has also served as a co-author with Colson, the former Nixon administration official who served time in prison for his Watergate misdeeds and then founded Prison Fellowship, a ministry serving inmates.

In his introduction to “Prisoner of Conscience,” Colson calls Wolf “a modern-day William Wilberforce,” the 19th-century member of the British Parliament and social crusader credited with persuading the British Empire to end the slave trade.

Sadly, the work of Wilberforce remains unfinished, as Wolf writes in often-painful detail.

“Prisoner of Conscience” is a worldwide survey of despotism. From famine in Ethiopia to genocide in Sudan to the fine-tuned machinery of repression in China, from the Soviet gulag to the jungles of Ecuador, Wolf circles the globe to make his case. All too often in these domains, where crimes against humanity are the normal run of things, that case has fallen on deaf ears.

Wolf’s anger at this lack of response — on the part of the perpetrators as well as on the part of the West and the United Nations — shines through in his straightforward prose.

And he calculates the human cost associated with the indifference of what Martin Luther King Jr. called “the appalling silence of the good people.”

“Wei Jing-Shen, who spent years in prison and is referred to as the father of Chinese democracy and the Chinese Nelson Mandela, once told Chris Smith [Wolf’s New Jersey Republican colleague in the House] that when American leaders pander to Chinese dictators, they beat dissidents more in the prison camps,” Wolf writes. “By contrast, when American leaders are tough, predictable and transparent, ‘they beat us less.’”

Wolf also cites human rights observers who say that “beatings have gone into overdrive during the Obama administration.”

But Wolf gives President Barack Obama credit for his administration’s role in deposing Libyan leader Moammar Gadhafi and for committing U.S. troops to aid in the fight against the Lord’s Resistance Army, which has conducted a two-decade campaign of terror and violence in Uganda.

He had less-kind words for the administration’s timid response to the murderous rampages against Coptic Christians in Egypt, and he fears for the future of the Chaldean Christian community in Iraq. “They seem afraid to use the word Christian,” Wolf said in the interview.

He has turned his righteous indignation into some legislative victories and is well-positioned to win more as chairman of the Appropriations Subcommittee on Commerce, Justice and Science. He is a constant letter-writing nag, always urging more and quicker action.

One of the great advantages of his job, Wolf said, is “you can see something on ‘60 Minutes’ that really bothers you and come into work in the morning and do something about it.”

Those kinds of small victories can mean a lot to people living in misery, while rarely affecting the big picture immediately. But the odds don’t seem to deter Wolf, who quotes President Abraham Lincoln — “the abolition of the slave trade by Great Britain was agitated a hundred years before it was a final success” — and notes that Wilberforce spent three decades in his anti-slavery crusade (about the same amount of time that Wolf has been in Congress).

And Wilberforce didn’t have satellite TV, the Internet or smartphones.

“We can’t say that we didn’t know,” Wolf writes. “We must stand up and speak out for those who suffer around the globe — no matter how hard the battle, nor how long it takes.”