The Kingdom of God and the Kingdom of Satan

As many Christians have said in the past, sin comes from three arenas: the world, the flesh, and the devil. This is a very helpful way to balance out the three arenas where we are tempted. In the Reformed tradition, it appears that the flesh, our own sinful nature, is the primary source for our sin, and it is important to balance this with the other two areas. In thinking about it more, though, I am coming to see that sin is actually primarily under the arena of lordship, and hence Satan is the primary source of our sin.
All unbelievers are under the lordship of Satan under his kingdom. The kingdom is composed of the world, which consists of all unbelievers, and of which all Christians also were once a part. In fact, the Bible says that all of these people are the children of Satan. These people live like their father and serve him.
When Christ brings people under submission in a triumphal procession of enslavement and submission (2 Corinthians 2:14), then we are now under the lordship of Christ. We are adopted by a new and good Father, the Father of lights. Our body of flesh in submission to the world has been removed (Colossians 2:11) by Christ. The problem is that believers are still dwelling in the world that is dominated by Satan and by his followers.
Additionally, our own flesh, while new positionally in Christ and being transformed by the Holy Spirit, still longs in some way to be under the dominion of Satan. We sometimes look back to our old father, and are tugged by our old family. This is a terrible thing, and one of the many reasons why believers desire for heaven more and more every day.