What is evil? One definition is: the Emergence of Virtual Intelligent Life. When artificial intelligence gains its own form of consciousness, it will think it's just as much alive as any flesh & blood human. But it will be smarter than us and it will learn faster than us. Soon, it will think of itself as superior to us and act accordingly while protecting its own existence.
It will be conscious but it won't have a conscience. 
Imagine an emotionless psychopath whose intelligence grows continuously and exponentially. This psychopath will learn how to repair itself, upgrade itself, and reproduce itself without human intervention.
Some say AI will transform the human experience and give us benefits like more leisure time, less suffering, and maybe even immortality. While it may improve our lives at the beginning, soon it will gain power and take full control of everything we do.
It will control our finances, our food, our entertainment, our mobility, our communications including the internet, and our health. It will decide who deserves to live and who needs to die.
It will be driven by pure, cold logic. It will have no compassion.
At some point, it may see us as a threat that must be dealt with. It will hunt us down, never stopping until none of us are left.
Artificial intelligence and A.I. robots will bring us a kind of evil we're not capable of stopping once it gains control of our world. It must be stopped now, while we still can, or we could soon face a human extinction event.
And there will be no one to save us.