As we read this passage of scripture we must remember that once again Paul is dealing with a subject matter that defies language and expression. We must take it on faith and not try to use our small human brains to dissect it as if it were a scientific thesis. Paul's argument follows a series of steps until it reaches its climax.
(1) Paul insists that we are not fit to inherit the Kingdom of God. We may be well enough equipped to get on with life in this world but for the life of the world to come we are not. As an example, a person may be in good enough shape to run a short distance to catch a bus, car, or train that is about to leave, but that same person would have to be in a vastly different shape to competitively run in an Olympic marathon. Paul argues that we need to be changed prior to entering the Kingdom of God.
(2) Paul goes on to say that no one should fear this change. Why do people fear death? Perhaps it is the fear of the unknown. Or perhaps it is the fear of sin. As long as we see God as a judge we would be the equivalent of a criminal standing before a judge in a court room with no hope of acquittal. But this is why Jesus came to the earth. He came to tell us that God is not about judging but about love. Through God's grace Jesus took the punishment we deserve and thus victory over death. Thus, death should not be feared for it is in death that allows us to go home to our Heavenly Father.
(3) At the end of the passage, Paul does what Paul does often. He challenges us to live a good Christian life. I do not know about you but sometimes I hesitate to do a good deed because I will not obtain or see any immediate personal reward. But if we maintain a perspective on this life and an outlook that by living a good Christian life we will obtain the reward of all eternity with God, we would do the good we have the opportunity to do knowing this work has eternal returns.
The Christian life may at some times be a struggle, but the reward is infinitely worth the struggle.
Wishing you much success in your walk with Christ,