Proverbs 4:14-15 Don't do as the wicked do, and don't follow the path of evildoers. Don't even think about it; Don't go that way. Turn away and keep moving.
We know not to do evil...but here it says not to even think about it! It even tells us to keep moving. We are not to dwell on why somebody does evil, or how. We are not suppose to even take time to notice what their life is like.
I believe that there are two reasons for that... if we are busy with evil in any way we can not have our mind on God. And evil is such a strong power we can easily be pulled in, deceived by it.
God's word tells us to constantly renew our minds. We are to keep our mind on God... to stay busy, to keep moving forward in God. We are not to even stop and ponder evil!
I think we need to become extremely aware of all the ways evil creeps into our lives. Is it through people, through books, through TV? We must be aware, we must take notice we must turn away and keep moving toward God.