V.1-17 He turns away from human intelligence and brings them back to truth. We are to turn our eyes and our thoughts heavenward. He reminds them (and us too) that they are dead (with Christ) and their life now is hid with Christ in God. No mixing — it is one or the other which takes up our attention. If we realized that we are dead then there would be little attraction to the world.
V.4 Paul would always draw us to Christ and His appearing.
V.5 They (and we) need to be reminded to consider all these things to be dead.
V.8 If we agree that the things in verse 5 should have no part in our life, how about the things in this verse? They also belong to the old life, and God says it is dead.
V.18-25 Particular instructions for different classes of people. The first verse of the next chapter connects on to the end of this one.