While slavery was wrongly tolerated for some time, it was the Christians that initiated the movement to end slavery. In fact today's slavery battle in the Sudan is being led by Christian pastors in American, namely Dr. Kennedy in Florida. He has been at the forefront for years.
To the best of my knowledge the bible, which is the written basis for Christianity, doesn't condemn slavery or indentured servitude. It does give guidelines for how slaves (and masters) are to be treated and it does set limits on slavery (a slave can only be kept permanently with his own permission).
While Christians have indeed been at the forefront of anti-slavery movements in this country and everywhere else, the concept of slavery isn't anti-biblical.
Personally I'm against it as it is an inefficient use of resources. Free men produce far more for themselves, their employers and their society.
God Save America (Please)