We can't eliminate the weeds in a garden by ignoring them. The beauty of flowers and the productivity of vegetables are obvious, but if we're apathetic about weeds, the neglect will show.
The same is true of human consciousness and experience. Evil in human experience doesn't go away by itself. A healthy attitude and good thinking produce some positive results, of course. But when evil thoughts assault us, it's just like dirty dishes in the sink or weeds in the garden or undone tasks on the job—they just sit there until we do something about them.
We learn early, if we have parents who teach us, to resist the temptation to steal, hurt others, and lie. Our parents teach us to control such thoughts. And if we learn that by understanding something of the allness and harmony of God, we can just as forcefully resist suggestions of illness and disease, we have a good start on gaining control not only of actions but feelings of the body.