Because it contains no yeast, this dark quick bread takes only a minute to knead and does not require rising time. The dough will be sticky and wet as you knead it. The loaves brown quickly and may appear done before they really are.
Combine first 4 ingredients in a medium bowl. Lightly spoon flours into dry measuring cups; level with a knife. Combine flours, sugar, salt, baking powder, and baking soda in a large bowl; make a well in center of mixture.
Add buttermilk mixture to flour mixture, stirring just until moist; stir in raisins. Stir with a wooden spoon until dough pulls together in a shaggy mass. Let rest 2 minutes.
Turn half of dough out onto a lightly floured surface. Knead 1 minute with floured hands (dough will feel tacky); shape dough into a 6-inch round loaf. Place on a baking sheet dusted with cornmeal. Repeat procedure with remaining dough. Make 3 diagonal cuts 1/4-inch deep across top of each loaf using a sharp knife.
Bake at 400° for 20 minutes. Reduce oven temperature to 375° (do not remove loaves from oven); bake an additional 15 minutes or until bottom of each loaf sounds hollow when tapped. Let stand 15 minutes before slicing.