In 2 Corinthians 4:13-18 Paul writes to the church in Corinth concerning a confident hope and a proper perspective. The hope and perspective that Paul describes is very helpful for us as well.
We must remember that Paul is writing to a church that has had many difficult times (see any chapter in 1 Corinthians) and to a group of people who were experiencing some sort of affliction (4:17).
However, Paul delivers a confidence that is found in his future bodily resurrection; a confidence that is founded in Christ’s bodily resurrection (4:14). This is the point of hope and perspective for Paul. There may be also sorts of difficulties around him, but knowing what the future holds brings a proper perspective for Paul.
Paul brings this encouragement to the church in Corinth so that they will not lose heart (4:16).
Now for Paul it is not just about the future. Our passage concludes with a description of the inner work of renewal. A proper perspective understands that we are in the process of change. This process (a.k.a. sanctification) is to help us to be confident in the Spirit’s work and the Spirit’s completion of the work (5:5).
It is important to note that Paul is not giving some sort of Gnostic interpretation of the spiritual (unseen) world versus the physical (seen) world. Paul is not giving a dualistic understanding of the world.
What Paul is emphasizing is the need to focus on the work of the Spirit in us. Because of sin our bodies are decaying and the world around us is dysfunctional. But God through his infinite might have started a process within us (as Christians) that will resurrect these decaying bodies and will bring order and shalom to the world (cf. Romans 8).
We are not to focus on the decay and the wasting away, but on the inner renewal of the Spirit and our future bodily resurrection.
So, let us focus on the proper perspective. God is changing us and this is a change that will be completed fully when Christ returns to earth.