Do you actually think "lucifer" is a real entity? Or are you using this in a metaphorical construct as the shadow side of "god." If it is an entity then you have to ask the deeper question, why would the "god" character allow something he created to cause such harm. It would be like watching your child beat the crap out of all the kids in the village and stand back and say...free will. The responisbility is on the parent. And in the biblical god case, even more so. if you created something and it caused death and destruction, then....reasoning suggests that.......