In a large mixing bowl, stir together starter, water, whole wheat flour, and vital wheat gluten with a large spatula until combined. You will have a rough, sticky dough. Cover and allow it to rise for 1 hour. Remove lid, sprinkle salt over dough, and gently pick up one side of the dough, fold it in half. Repeat with all four sides of dough. Cover and allow to rise for another hour. Repeat 2 more times for a total of 4 folding times. Cover and place in the refrigerator for 12 hours or longer. Remove dough from the refrigerator. Flatten dough into a rectangle. Sprinkle heavily with cinnamon and raisins. Fold dough in 3rds, pinching the edges together to seal the edges. Turn dough and fold in 3rds, pinching to seal edges. Line the bottom of the clay baker with parchment paper or foil. Place loaf seam side down in a clay baker. Preheat oven to 450 degrees F. Remove the lid from the baker and fill with water. Allow the water to soak the lid for 10 minutes. Slash the loaf with a sharp knife. Empty the water from the lid and place it on the clay baker. Place the covered baker into the hot oven. Set the timer for 35 minutes. Reduce oven temperature to 400 degrees. Remove the lid and bake for an additional 12-15 minutes. Remove clay baker from oven. Remove loaf to a wire rack to cool. 12-14 slices.