Verses 1-23
Paul's example (9:1-23)
The principle Paul has been teaching in the previous chapter is that no matter what rights Christians may have, they should be willing to sacrifice those rights for the sake of others. He now demonstrates that principle with a number of personal examples.
Paul has the same rights as others, and in fact more, since he is an apostle. But he does not always exercise his rights. Some people have misunderstood this and think that he is not an apostle at all. Paul points out that the existence of the Corinthian church is living proof of his faithfulness in his apostolic ministry (9:1-2). Paul and Barnabas (and their dependants) have as much right as the other apostles to travel and live at the expense of the church. But they deny themselves this privilege and work to earn their living, so as not to be a financial burden to the church (3-6).
Any workers, whether they be soldiers, farmers, shepherds or servants of the church, have the right to receive their living from their occupation (7). This principle is found also in the law of Moses. An animal that treads out the grain is allowed to eat the grain as it works (8-9; Deuteronomy 25:4). Just as the farmer expects to get something to eat from the results of his work, so does Paul. He has worked hard in spiritual service in Corinth and he is entitled to a material reward (10-11).
Others have received gifts from the Corinthians, but Paul has not. He has not exercised his right, because he does not want financial matters to be a hindrance to the work in Corinth (12). Both the law of Moses and the teachings of Jesus show that Paul has the right to claim financial support from the Corinthians (13-14; Deuteronomy 18:1; Luke 10:7-8).
In writing like this, Paul is not trying to shame the Corinthians into giving him financial assistance. He prefers things as they are. He preaches the gospel, not because he wants to boast about his work or income, but because he is compelled to preach (15-16). Whether he preaches willingly or not, he must preach. His reward is the knowledge that he preaches freely without claiming his rights to financial support (17-18). He sacrifices his own freedom in order to serve others, his aim being to get people to listen to his message and accept it (19). This applies to all whom he helps, whether Jews, Gentiles, or 'weak' Christians such as those who will not eat food offered to idols (20-23).
Verses 24-27
Necessity for self-discipline (9:24-27)
Christianity is a life of effort. As runners in a race strain to the full to win the prize, so Christians should put all their effort into whatever they do (24). As athletes undergo strict training in their pursuit of victory, so Christians should deny themselves lawful pleasures and foods in order to be more useful for God (25). Paul has purpose and effort in all that he does. He is like a runner who heads for the finishing line or a boxer who aims to land his punches. He spares no effort in his program of vigorous self-discipline to keep himself fit. He realizes that it is dangerously easy to warn and instruct others, then fall into sin himself and be disqualified (26-27).