no offense is taken. It's best that we first stamp out our own insecurities, before dealing with those of others. God and Satan both dwell within us, and I believe it is part of our faith to try to rid ourselves of Satan to find salvation.
And also- no one has answers. That's why we're human. Ask God the questions, and in His time, in His way, He'll answer them.
Such is our faith,
I don't know what has gotten you thinking that God and Satan both dwell inside all of us but you couldn't be more wrong and that is sad. If God is in you then Satan isn't. The Bible makes it pretty clear when it talks about having to bind the strong man to be able to take his house.
Real Godly people are not ever and can never be possessed by demons or satan. Influences maybe, Troubled sometimes yes. But the 2 can't exist in the same place.