Declaration of human rights and freedoms.
Chapters 8-10 deal with how Christians deal with their pagan religious past. Here in chapter 9 Paul explains how Christians are to express their freedom.
1. Paul's freedom and rights. (v1,2) Paul is an apostle - very special people - commissioned by the Lord Himself. He explains his rights in the light of being an Apostle (v3,4). He has these rights, because we have the basic right to get some benefit and rights from our work (v7-12). Supports the argument from the Deuteronomy 25:4. The local churches should support Paul (v11-14).
2. But (v15) Paul does not use or claim his rights. Paul supported himself financially (as a tent maker). Why (v18) - to offer the Gospel for free. Paul's rights are not as important as the work of the Gospel. To Paul, his rights are not sacrosanct (v19-23) for the sake of the Gospel. Some examples of people claiming their rights.
3. How do we do this (v24-27). We need discipline (v25) and training. We need to practice over and over. We need to do it, even if we do not feel like it (v26-27). We are to train to live for others. Compare Jesus - Philippians 2 - He gave us His rights for our good.