Preheat oven to 375 degrees F. Line a baking sheet with parchment paper; set aside.
Combine the raisins and whiskey in a small saucepan. Place over medium heat and bring to a simmer. Once it reaches a simmer, remove from heat, cover, and steep for at least 1 hour. When finished, drain the raisins and reserve the whiskey to use in the whiskey butter.
In a large bowl, whisk together the flours, baking soda, and salt. Use a pastry blender or your finger tips to blend the butter into the flour mixture until coarse crumbs are formed. Most of the butter should be about the size of small peas, with a few larger pieces throughout. Stir in the whiskey-soaked raisins. With a wooden spoon, stir in the buttermilk just until the dry ingredients are moistened and the dough comes together.
Turn the dough out onto a lightly floured counter and knead lightly until the dough is smooth, but still slightly sticky. Use as little extra flour as necessary to knead the dough.
Pat the dough into a 6-inch circle. Place the dough circle onto the prepared baking sheet and score the top of the dough ½-inch deep to form a cross.
Bake for 30 minutes, or until an instant-read thermometer reads 190 degrees F in the center of the loaf. Remove to a cooling rack. If you plan to serve the bread warm, you can cover it with a towel to keep it warm. Any leftover bread can be wrapped in plastic wrap and stored at room temperature for up to 3 days.
While the bread bakes, prepare the Irish Whiskey Butter. Microwave the whiskey and sugar together for 20 seconds, and then allow to cool to room temperature. Place the softened butter in a medium bowl, and beat in the whiskey mixture a little at a time, until completely incorporated. You can place the butter in an airtight container or wrap into a log with plastic wrap and store in the refrigerator for up to 2 weeks.