Preheat the oven to 350 degrees F (175 degrees C). Grease a cast iron skillet.
In a medium bowl, mix together the flour, baking soda and sugar.
Toss the raisins with the flour mixture until coated.
Make a well in the center and add the egg, buttermilk, and melted margarine.
Stir until all of the dry ingredients are absorbed.
Turn the dough out onto a floured surface and knead for a few quick turns just to even out the dough.
Handle the dough as little as possible.
Pat into a flat circle, and place into the prepared pan.
Bake the bread for 40 to 45 minutes in the preheated oven, or until the edges are golden.
