In a large mixing bowl, combine flour, sugar, cinnamon, baking powder, soda, and salt. Cut in margarine. Make a well in center. Add sour cream, 2 tablespoons milk, and raisins, stirring till just combined (add a bit more milk, if needed).
On floured surface, gently knead 8-10 stokes. Pat dough to 1/2" thickness. Cut with biscuit cutter, dipping in flour between cuts. Place on baking sheet.
Bake at 450 degrees F (230 degrees C) for 10-12 minutes. Cool slightly on wire racks.
Stir together confectioners' sugar and 2 teaspoons milk. Drizzle over biscuits. Sprinkle with additional cinnamon and sugar, if desired.