For in Christ the fullness of God lives in a human body, and you are complete through your union with Christ. (NLT)
When we complete our meal there is nothing left on the plate. We are finished. When we complete the cruise to the Caribbean and return to our home port the cruise is complete. Simply stated the word complete means finished as in there is nothing more to do.
The gospel is simple. Jesus said, when asked how you become born again, no one can enter the Kingdom of God without being born of water and the Spirit. We accept Jesus as our Lord and Savior, become baptised, and receive the Holy Spirit, the Spirit of Christ. It is complete. We are saved by Grace. Once. There are no additional steps we have to take for our salvation at the end of this age. It is finished.
Some seem to think we have to continuously please God to keep our salvation. No, it was complete and irrevocable when we became born again, when we were saved and Holy Spirit came to us. This is not a license to sin, but grace to know we are a work in progress and each at a different position in our salvation walk.
We are no longer sinners on a long walk to eternity without God. We were saved by His Grace, but we still mess up. We still find ourselves doing the wrong thing, saying the wrong thing. This is because our soul is still in need of change. Our mind is in need of renewal. We still sometimes think and act and talk like we used to.
Our Spirit man is complete. Jesus is in us. We need His help in renewing our mind and our actions to be like Him and not like our old self. We cry out daily for Him to change us and as we release more and more of our old self to Him it happens. We become more Christ like in our thinking and fall to our old ways less and less.