William Carey: radical disciple—meaning?

Here is a thought-provoking quote about William Carey from Howard Norrish’s article “The Great Century” in Mike Barnett with Robin Martin, eds., Discovering the Mission of God: Best Missional Practices for the 21st Century (Downers Grove, IL: InterVarsity Press, 2012), 270: “Carey believed in radical discipleship and was committed to a biblical worldview.” I am interested in unpacking the first claim about Carey: “radical discipleship.” What did this mean exactly for Carey?