Do you believe in Satan?

Whether it's right or not, it's possible. Unless you're a Christian of course. If you're not Christian but believe in God, you're most probably just a believer in positive energy. God is seen as only a positive thing, so it's optional whether you want to believe in the negative side.

Personally, I believe in God and Satan.

I do not believe that Satan is a being that is hiding under us with a "Stick".

I believe Satan controls the after life of people who did not believe in god, or did not ask for forgiveness.
He is just the opposite of God in my eyes, he is negative and is in the lake of fire.