The aim of your sermon is to help God’s people understand that the Spirit of God is at work to sanctify them, and that his work takes time and is connected with the preaching of the gospel. Before coming to this application, you will need to explain Paul’s argument and why it was necessary. Pay attention to the two different ways in which people approach God and their different outcomes. It will also be a good idea to comment on why the law is so attractive to us, and to once again affirm that the old covenant law has been fulfilled by Christ and has thus come to an end.