Demons are evil because they are under a condition that has made them by nature corrupt. Jesus vindicates Gods act of creation by telling us that demons are in punishment from God to a damned spiritual realm that is a dry,desolate, and restless hell. As they pass through it, they are seeking rest from their torment, and humans are a attempt to attain relief. But this punishment and seperation from God has cause them to go mad (as demonologist understand them to be) and unclean.
Consider any creature that lived in conditions where your every need was met, and then one day you were force to eat only dry food and survive with no water anywhere and no help from anyone, while attempt to find anyway possibe to atleast relieve your conditon. After a while in such conditions, most natural creatures would began to go mad, until they lost a sufficient bodily health to support their madness, then die. Gods vindication by Jesus's words is in the understanding that God would not create a creature that is a constant snarling, ripping, tearing, unclean, clawing, biting, destructive beast to no end by nature. Jesus words make sense. Demons are fallen angels that lost their original divine nature, and apparently Heaven. For help with being convinced of the spiritual realm, go to youtube and look at the "Asheville N.C. Highschool ghost" clip. If you consider societies character at all, then this News report should give you more to think about in coming to terms with such a concept. God Bless everyone, and remember, God gave through Jesus everyone the spiritual authority to command any questionable spiritual experience to leave you alone to your creators grace, which is full of peace. See you all one day in Heaven!

And what if one tryed to be good.but not in the sense we think just as let live and only fight if nessery. a garden of sorts not good but not bad. humen?