If you are not aware of the movie coming out about the story of John Newton's and William Wilberforce's Christian effort to end the slave trade called "Amazing Grace," I want to recommend it to you.

There are also some study guides for high schoolers on the movie's website at http://www.amazinggracemovie.com/.  These guides focus on historical facts and are concerned about social justice in fighting against human slavery, but mention positively the influence of Christianity throughout the story that is told.  They are not bible study guides, but could be of use in a Christian school.  Also, there are materials for churches at the following locations:

http://www.amazinggracemovie.com/ag_sunday.php
http://www.amazinggracesunday.com/
http://www.amazinggracesunday.com/us/index.html

The World Council of Churches is involved in this, which doesn't convince me that the movie's Christian message will be adequately free from hints of the "social gospel."  The company that wanted the movie made wanted the story to be about the key characters' Christian faith, but compromised with the producer who wanted the story to be about the abolition of slavery.  Nevertheless, if you distinguish the politics from the Christianity in the movie, this is a significant film for Christians to see.

To get the fuller story of William Wilberforce's Christian faith, you should read John Piper's short book that has just come out titled "Amazing Grace in the Life of William Wilberforce."  You can even read it online here for free!