"[I]n the New Testament religion is grace and ethics is gratitude"

Thomas Erskine of Linlathen, quoted in Stott, The Message of Romans (IVP 1994). Stott, in turn, cites Bruce, The Letter of Paul to the Romans, in The Tyndale New Testament Commentaries (IVP and Eerdmans 1963, 2d ed.). Bruce cites Erskine's Letters. (Whew!)