In the 12th chapter of Revelations we read about a war in heaven. This is a war that resulted in the dragon (Satan), together with a third of the angels who followed him, to be cast out of heaven into the earth.
"And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him." – Rev 12:10
This is an ancient battle that not only continues to this day, but intensifies as we draw closer to the end-times. When Satan and his followers (demons / evil spirits) were cast down to earth they certainly had no intentions to make this world, created by God (their nemesis), a better place. You don't have to believe in this raging battle in order for it to exist. In fact, it is becoming harder to ignore its existence, since it only makes sense that Satan will increase his efforts as his time runs out.