"The film Amazing Grace implies that Newton converted to evangelical Christianity and, as a result, became an abolitionist. This actually is NOT true. While both are true—eventually—the one was not caused by the other. Newton, in fact, was a slaver. His job was to sail slaves to the Americas where they were sold. Newton continued to do this well after his so-called conversion. Newton became an evangelical in 1748. He continued selling slaves until he retired from the sea in 1754 because he wanted to become an Anglican priest. Newton was quite happy to use violence against slaves and used torture to wring confessions from those he thought guilty of planning their own freedom.  A third of a century after his retirement as captain of slave ships Newton came out in support of abolitionism. So, if his conversion to evangelicalism made him an abolitionist, it took almost four decades to do so."

Moorfield Story Blog: Evangelicalism and Slavery: Historic Allies Not Enemies
(via AZSpot)