Preheat oven to 375°. Combine dry ingredients in a large bowl. Cut butter into mixture with pastry blender. Add buttermilk, mix thoroughly into soft dough. Add raisins. Knead dough for about 3 minutes or until smooth. Form dough into 7 inches flat round. Cut a cross 1/2 inch deep into the center of the dough. Bake on a greased baking sheet for 40 minutes. When cooled, cut into wedges and serve with butter.