That's an interesting and well-established view, but the argument that Christianity led to the abolition of slavery during the middle ages isn't well-supported by primary source evidence and depends instead on shaky assumptions about religion and economics. Perhaps the most significant recent support for the abolitionist view is Jeffrey Fynn-Paul's short article "Empire, Monotheism and Slavery," Past and Present 205 (2009): 3-40.

Fynn-Paul's argument that Christianity ended medieval slavery requires some qualifications. First, it conforms with a tendency to project modern assumptions about Christianity—i.e. that Christianity is inherently opposed to slavery—into our studies of periods before the 18th- and 19th-century abolitionist movements. This assumption has been seriously challenged only during the last 10-20 years, so Fynn-Paul was still able to draw on a substantial body of supporting literature and relegate debate largely to a single footnote. Insofar as he considers primary sources, however, he admits a certain "sparseness of evidence" and "of course the reality was usually less than perfect."

Second, Fynn-Paul wasn't arguing about abolitionism as such, but rather that Christians grew resistant to enslaving fellow Christians, whereas Muslims grew simultaneously resistant to enslaving fellow Muslims. The creation of these two "no-slaving zones" caused competition for slaves from surrounding areas, like the Russian steppe and sub-Saharan Africa. As competition drove the cost of slaves up, Muslims, benefiting from the booming economies of the medieval Middle East, were gradually able to drive Christian consumers out of the market. In this case, abolition in Europe was driven by economics and only indirectly influenced by a Christian anti-slavery ethos. Again, Fynn-Paul projects modern assumptions onto the premodern past, here examining medieval societies in tho terms of present-day free market economies. I consider this a risky endeavor.

Fynn-Paul's study should also be understood as part of ongoing debates about medieval slavery, which in many ways continue to build on the classic studies of Marc Bloch. Past and Present has published a number of such articles, with particular attention to the roles of gender and economics in shaping slave societies. I also recommend Wyatt's incisive study of the influence of 19th-century abolitionism on current scholarship about slavery.

• Marc Bloch, Slavery and Serfdom in the Middle Ages, trans. William R. Beer (Berkeley: University of California Press, 1975).
• Ross, Margaret Clunies, “Concubinage in Anglo-Saxon England,” Past and Present 108 (1985), 3-34.
• Stuard, Susan Mosher, “Ancillary Evidence for the Decline of Medieval Slavery,” Past and Present 149 (1995), 3-28.
• Devroey, Jean-Pierre, “Men and Women in Early Medieval Serfdom: The Ninth-Century North Frankish Evidence,” Past and Present 166 (2000), 3-30.
• McCormick, Michael, “New Light on the ‘Dark Ages’: How the Slave Trade Fuelled the Carolingian Economy,” Past and Present 177 (2002), 17-54.
• Rio, Alice, “Freedom and Unfreedom in Early Medieval Francia: The Evidence of the Legal Formulae,” Past and Present 193 (2006), 7-40.
• Fynn-Paul, Jeffrey, “Empire, Monotheism and Slavery in the Greater Mediterranean Region from Antiquity to the Early Modern Era,” Past and Present 205 (2009), 3-40.
• Wyatt, David, “The Significance of Slavery: Alternative Approaches to Anglo-Saxon Slavery,” Anglo-Norman Studies 23 (2000), 327-47.