And if Christ be in you, the body is dead because of sin; but the Spirit is life because of righteousness. (Rom. 8:10)

This is another way of describing the separation in each believer between the new creature in Christ and all that remains outside of that new creation — and remains carnal. When we are saved, we are planted into His death – and we find that our body of sin is dead because of His death for our sin. We are also planted into His resurrection, and this joining of our spirit with Christ makes us alive with Him. The rest of the Christian life is a matter of us coming to walk in the Truth of these finished realities – we have to lose what is dead in order to find Christ as our life.
Note that all of this is the result of CHRIST IN US. Until Christ is in us, there is no separation between life and death in us – but there is only death. Until Christ is in us, there is no means by which we can be set free from untruth, because there no Truth in us. In Christ are all things that are of God, because all of the fullness of God dwells in Him. What an amazing Truth: God is in Christ and Christ is in us. The plan of God: The Father, the only begotten Son, and all of those who are in the Son.