Heat small skillet over medium heat. Add cumin and stir until aromatic and lightly toasted, about 2 minutes. Grind cumin in mortar or spice mill. Mix pomegranate molasses, olive oil, garlic, oregano, salt, pepper, cinnamon, and cumin in 1-gallon resealable plastic bag. Add lamb; chill at least 1 hour and up to 4 hours.
Remove lamb from marinade. Thread 1 lamb piece and 1 red pepper piece on each skewer; place on baking sheet. Do ahead Can be made up to 2 hours ahead. Cover and refrigerate.
Prepare barbecue (medium-high heat) or preheat broiler. Sprinkle kebabs with salt and pepper. Cook, turning often, about 4 minutes for medium-rare.