Is There a Reality of Evil in Milton?

There's a potency about evil that just can't be brushed away. I think the right path is to exist such that the possibility of evil remains open, but that you choose the good. The tower of babel is raised by human beings so that pinnacle will hit heaven. We are furthering our creation by our actions and choices. And it seems to me that in order for ther to be good, there has to be evil. But i don't think that evil per se, is built into the structure of the world. It doesn't seem to me either that it's tragedy that takes the spirit out of people.