@Sevan,
You realize that 'Satan' is not answer to you question why evil exists right?
Because if humans can't do evil without outside influence (Satan), why would Satan be able to do evil without outside source?
- Satan, supposedly created as a perfect, holy angel to serve God in righteousness.
- Humans, supposedly conceived in sin, their every thought wicked, and with a treacherous heart.
Does it make any sense to say that wicked humans need Satan to do evil, but a holy angel can come up with wicked stuff all by himself?
These myths don't make any sense. Let them where they belong...a couple thousand years in the past...