Even though sin dwells in our bodies, in this text, Paul instructs us to present our bodies to God as though it is holy and acceptable. This is an act of faith. We trust that because of the sacrifice of Jesus Christ on our behalf, the Father will have mercy.
Yet we are to present our bodies as a sacrifice. To give ourselves over to be crucified. This is our spiritual service to God.
And our willing crucifixion accomplishes two things: 1) It sanctifies us so that we are no longer conformed to this world 2) It transforms us into newness of life in Jesus Christ.
And so we begin upon our journey toward perfection, which is to be like the One who voluntarily laid down His life for us. It is only because of the mercies of God that we are being made complete.