Please read the passage before the commentary.
God wants us to have holiness, free of attacks on our immune systems, free from all cancers, free to be as God is, holy completely. Do we want this for ourselves? Paul encouraged his Thessalonians to continue on their path to holiness.
We have been initiated into this holiness of God. This is the work of our baptism. We must continue to grow. How do we grow? Paul spoke of honoring one another, of not taking advantage of or exploiting one another.
Furthermore, to enable us to be like God, God gives us God’s Spirit to us. God wants us to be holy, and God makes it possible for us to holy. God wants us to be holy, like God. God want nothing less from except holiness.