Christianity Today gives Amazing Grace a pretty good review. The film hasn't arrived at our little backwater yet, but we're looking forward to seeing it when eventually it does. William Wilberforce was an impressive man, motivated, as were so many abolitionists throughout history, by his sense that Christ wanted him to do what he could to fight the injustice and inhumanity of the slave trade.
Rodney Stark, in his excellent historical work titled For the Glory of God, points out that had it not been for Christians and the Church, slavery would not have been eradicated in Europe after the fall of the Roman empire, and when it rose again after the discovery of the New World, it was both the Church and the work of Christians like Wilberforce which eventually got it abolished in the Western Hemisphere.
There is nothing in any other religious tradition, and certainly nothing in the philosophies of naturalism or materialism, that affords grounds for condemning slavery. Indeed, Islam's founder, Mohammed, himself owned slaves.
To the extent that slavery, which has been practiced all through history and all throughout the world (and still is today), has been meliorated or abolished, it has been because of the efforts of people operating out of a Judeo-Christian worldview which teaches that men are made in the image of God and are loved by Him. As such they have individual dignity and are all equally precious in God's eyes. Each man is the property of the Creator, and it is therefore an affront to God to treat as one's own property a man or woman who is one of His children.
If, though, we abandon this worldview we must also abandon the notion that man has any special dignity or worth or rights. If there is no Creator then if one has the power to enslave another there can be nothing morally wrong with doing so. In a world without the Christian God might makes right, and owning people is no different, morally speaking, than owning horses.
RLC