Preheat oven to 350° F. Grease a 9-inch square baking dish with margarine.
Place bread cubes in a large bowl.
In a medium bowl, beat soy milk, eggs, brown sugar, rum, vanilla, cinnamon, nutmeg, and raisins. Pour over the bread and mix thoroughly. Spoon bread mixture into the prepared baking dish. Let rest for 20 minutes.
Bake for 30 minutes or until a knife inserted in the center comes out clean. Serve warm with whipped topping on the side.