The eternal weight of glory spoken of in 4:17 is described in more detail in chapter 5. First our physical bodies "this earthly tent we live in (5:1)" is going to be replaced with a heavenly dwelling. We struggle in our physical bodies but there will be no struggle in our spiritual bodies. Our mortality will be "swallowed up" in immortality. Paul believes that this process in the life of the Christ follower has already begun. We groan and struggle but we also have victory and success because the spirit of Christ is at work within us. We will all appear before the judgement seat of Christ . . . for life or death depending on how we lived (10).
The ministry of reconciliation is the focus of the next several paragraphs. We have died in Christ (15) and now Christ is alive within us. Coming to Christ we have become the "new creation (17)" -- whatever we were before has been transformed. This transformation is one of those marvelous biblical "has arrived and is still coming" concepts. We are reconciled to God but we are "being saved". We are transformed and we are in the process of transformation. I like to think of it this way: I have become an adopted son of God. But I came into the household from out in the cold and do not know the standards of the household nor do I know what it means to be a son. The adoption is a done deal -- I am now a child of God -- but I am in process toward becoming like his Son. This journey, in my opinion, is the journey toward discipleship and, for the Christ follower, is a life long journey.
As Christ followers we are now engaged in the ministry of reconciliation. God was in Jesus reconciling "embracing" the world to himself. Now that we are adopted sons and daughters of God it is our ministry to be ambassadors for the house of God and to go out and invite others into adoption. This is the ministry of reconciliation. God is making this appeal through us to all the world "come and join the family!" Be reconciled to God!