First at all world is not divided into good and evil, the war between God and Lucifer don't exist.
The concept of good and evil is relative, what is good for someone can be evil to other and what is evil can be good.
The same is about downloading images and before anything the subject must be divided in three big categories:
1- People that download pictures for personal use and personal colections.
2- People that download pictures and use them in sites or distribute them.
3- People that download and use it for some comercial profit.
You cannot treat all the people that download in the same way, each category has its own rules and the division between "good" and "evil" is very subjective.
Don't think that people that download for personal use consider themself as evil, most of them are good people, consider themself as good and the downloading act has nothing of wrong, people have rights too and their rights are not decided by your will.
If you can them thieves the roles become inverted and who is on the evil side is you and not them.!

Stupidity also evolves!