Combine chickpeas, chopped bell pepper, red onion, tomato, cucumber, optional olives, and garlic in a large bowl. Add olive oil, lemon juice, oregano, parsley, and salt and pepper, and stir well.
If serving immediately, add feta cheese and stir very gently just before serving. If serving later, place salad in refrigerator for up to 4 hours and add feta cheese just before serving, stirring gently to combine.