The overflow is the abundance of God in the life of a Christian; often times culminating in visible results that can only fit into a supernatural description.
The Scripture assures that believers have their citizenship in Heaven; where God sits as the everlasting Father and Supreme Head (Phil. 3:20). We are further told that the earth is the Lord's and all the fullness thereof.
If therefore, our heavenly Father, to whom we belong, owns all things, then by right, and as declared in John 1:12, we His children are permitted to ive and walk in the overflow.
Because we belong to God, we are exempted from the confusion and certain woes that befall unbelieving men. However, because msot believers do not acknowledge their citizenship or are overwhelmed by a life of sin, they live below God's plan for their lives.