Having been raised in a pre-millennial Christian tradition, we saw the world as evil, everyone around us evil, and that things were only getting worse. Jesus was going to come down in a spiritual helicopter and 'rapture' us all away from this sinful mess. A quite pessimistic, destructive and, in my opinion, irresponsible way of looking at the world. It only encouraged detachment, aloofness, elitism, and a weird gnosticism
Moving to the post-millennial side of Christianity, we see a much more optimistic view of things. The world is indeed corrupt, sin happens, but things aren't getting worse, they are getting better. Indoor plumbing, iPhones, central heating, A/C, Christian philosophy, morals, and worldview growing from 12 Hebrew stiffs to a worldwide movement that converted an entire empire (thanks Constantine). The post-millennial view of the kingdom of Jesus and eternal life is both responsible and creative. It encourages engagement with the world around us and requires that we build.
Is man still inhuman to man? Does tragedy happen? Yes, of course. This is not a pollyanna-like naivety. The coming of the kingdom of Christ is an incremental, slow working of the yeast through the entire loaf. The kingdom doesn't happen all at once. Our microwave, want-it-now approach fits perfectly with our length of life, but is oh-so-short-sighted. But if we have a long-term view of the coming kingdom, death does seem as if it's only a nap and we raise our kids and build our communities in anticipation of the fullness and fulfillment of time, the coming of Christ.