Humans are valuable because I say so. If you agree, we’d better convince others of that, work to bring about a society which believes that, and oppose (by force if necessary, as it was in World War II, to use your example) those who want to treat people as things.
Matt himself provides a good response, noting particularly the contradiction inherent in any attempt to “convince” others of a mere preference. If “humans are valuable” only says something about Paul Wright, and nothing about humanity itself, then there is nothing to convince anyone of – they either agree or they don’t. You might as well try and convince them that they “should” adopt your taste in food – maybe they’ll listen and change their minds, maybe they wont, but you can’t say they should do so; your moral system doesn’t allow it.
This is a good point, but I think there is even more at stake in this debate. The difference between Christian and atheistic worldviews does not just influence whether real moral debate is possible, but also how it can be conducted. There is nothing stopping an atheist from adopting the position Paul outlines, and choosing to work with those who happen to agree with him, while (if necessary) fighting against those who do not. But Christianity allows, indeed calls for, something more.
Since it assumes, first that there is a real and ultimate difference between good and evil, and second that deep down everyone knows it, Christianity calls us not just to fight against those who do evil, but to seek their redemption. Philip Yancey’s excellent book The Jesus I Never Knew provides a discussion of the “Beatitudes” (Matthew 5:3-12, cf. also 5:38-45 and Luke 6:20-31), which helps explain what I mean:
Blessed are the peacemakers… Blessed are those who are persecuted for the sake of righteousness…. [Matt. 5:9, 10] The movie Gandhi contains a fine scene in which Gandhi tries to explain his philosophy to the Presbyterian missionary Charlie Andrews. Walking together in a South African city, the two suddenly find their way blocked by young thugs. The Reverend Andrews takes one look at the menacing gangsters and decides to run for it. Gandhi stops him. “Doesn’t the New Testament say if an enemy strikes you on the right cheek you should offer him the left?” [Matt. 5:39] Andrews mumbles that he thought the phrase was used metaphorically. “I’m not so sure,” Gandhi replies. “I suspect he meant you must show courage – be willing to take a blow, several blows, to show you will not strike back nor will you be turned aside. And when you do that it calls on something in human nature, something that makes his hatred decrease and his respect increase. I think Christ grasped that and I have seen it work.”
Years later an American minister, Martin Luther King Jr., studied Gandhi’s tactics and decided to put them into practice in the United States…. As riots broke out in places like Los Angeles, Chicago, and Harlem, King traveled from city to city trying to cool tempers, forcefully reminding demonstrators that moral change is not accomplished through immoral means….
The real goal, King used to say, was not to defeat the white man, but “to awaken a sense of shame within the oppressor and challenge his false sense of superiority…. The end is reconciliation; the end is redemption; the end is the creation of the beloved community.” (pgs. 121-122)
Men like Gandhi and King were willing to put their lives in jeopardy not only to free their own people from injustice, but to do so in a way that also facilitated the repentance and restoration of their oppressors. This kind of moral fortitude is possible only if you believe in a moral order that transcends oppressor and oppressed alike. This kind of sacrifice is possible only if you believe that the state of a person’s soul is infinitely more important than the state of his body. Only then is a person willing to give up their own life in the hope that it might save others – not only the lives of their friends, but perhaps even the souls of their enemies. Yancey continues:
King, like Gandhi before him, died a martyr. After his death, more and more people began adopting the principle of nonviolent protest as a way to demand justice. In the Philippines, after Benigno Aquino’s martyrdom, ordinary people brought down a government by gathering in the streets to pray; army tanks rolled to a stop before the kneeling Filipinos as if blocked by an invisible force. Later, in the remarkable year of 1989, in Poland, Hungary, Czechoslovakia, East Germany, Bulgaria, Yugoslavia, Romania, Mongolia, Albania, the Soviet Union, Nepal, and Chili, more than half a billion people threw off the yoke of oppression through nonviolent means. In many of these places, especially the nations of Eastern Europe, the Christian church led the way. Protesters marched through the streets carrying candles, singing hymns, and praying. As in Joshua’s day, the walls came tumbling down. (pgs. 122-123)