I think it is somewhat of a logical fallacy to lay the sin of slavery at the doorstep, exclusively, of the Catholics or the Puritans, or the Jews, or the Muslims, or any religion for that matter. That fallacy has been phrased in a recent newspaper article as “correlation doesn't imply causation” and as a Latin phrase that means “next to therefore because of”.
Virtually all societies have at one time or another engaged in and supported slavery, whether it was the Greeks of Plato’s time, or the Romans of Caesar’s time, or the Assyrians of Hammurabi’s time or even the North American Indians of prehistory: all of which took place long before Christianity in particular became a player on the stage of history.
What is really problematic about the connection between slavery and religion, as marvelously and awesomely and depressingly described in the recent book “In Defense of Atheism: The Case against Christianity, Judaism and Islam” (Michel Onfray, Penguin, 2005), is that the holy books of those three monotheisms basically tell the faithful that God (and how can you argue with him, her or it or their self-appointed representatives on earth?) says that it’s ok to enslave the Others as they’re basically subhuman in any case. Bad combination of faith and barbarism in anyone’s book.
As powerfully phrased by Gretta Vosper “author of With or Without God (Harper Collins), a passionately argued case for a post-Christian church”, “’Those who recognize the Bible’s claim to be the word of God as the monster in the tub with the baby’ are the ones who must throw that monster out with the bathwater” [MacLean’s, March 31, 2008].