1 Corinthians 9:19-20
19 Though I am free and belong to no one, I have made myself a slave to everyone, to win as many as possible. 20 To the Jews I became like a Jew, to win the Jews. To those under the law I became like one under the law (though I myself am not under the law), so as to win those under the law.
Paul is continuing his plea, which started in 1 Corinthians 8:1, that the strong Corinthian believers should curb their freedom in order to love and protect those in the church whose consciences were weak. The original arena for this discussion was the practice of eating meat that had some prior association with idol worship. Some felt free in Christ to eat this meat without qualm, but others saw them doing so and were tempted to go beyond what their consciences would allow. So, the freedom of some was causing damage to others.
In 1 Cor. 9:1-18, Paul has firmly asserted his rights as an apostle, particularly the right to financial support from the Corinthian church. But he voluntarily gave up that right (1 Cor. 9:12, 15) so that obligations to patrons and other financial issues could not possibly hinder the gospel. He is trying to convince the Corinthians by his own example that giving up your rights for the sake of the gospel is a loving act that follows the example of Christ and also benefits those whose faith is fragile.
Because Paul had given up his rights, he was completely free to act and had no obligation to anyone (1 Cor. 9:19), except to Christ. For that reason he could offer the gospel free of charge (1 Cor. 9:18). He follows that with the remarkable statement I have made myself a slave to everyone, to win as many as possible (1 Cor. 9:20). David Garland says: He exchanges his position as a free man with high status for that of a slave . . . . Slavery to Christ necessitates slavery to all (cf. 2 Cor. 4:5; Mark 10:42-45). . . . Paul does not lead from a secure position above others but from a position below them, incarnating the folly of the cross.
What Paul means by saying he made himself a slave to everyone becomes more apparent when he explains, I have made myself a slave to everyone, to win as many as possible (1 Cor. 9:19b). The Greek verb for win comes from the world of commerce and means to gain an asset or make a profit. By winning others to Christ, Paul brings about lasting spiritual value. Arguments about advantage were a common element in Greek rhetoric.
It is truly ironic for Paul to say, To the Jews I became like a Jew, to win the Jews (1 Cor. 9:20). Anthony Thiselton says, Since Paul was in fact a Jew, this formulation shows how radically he conceives the claim that in Christ he is . . . in a position transcending all cultural allegiances. Ask yourself whether you see identification with Christ as transcending all your own cultural allegiances. If not, you need a clearer understanding of your identity in Christ.
Those under the law (1 Cor. 9:20) probably means the Jews, although it could be a reference to Gentiles who converted to Judaism. More important is Pauls declaration though I myself am not under the law. Both then and now there are Christians who believe you must keep the Law of Moses — to the limited degree that is now possible — in addition to believing in Jesus, but Pauls statement demonstrates that they are headed in the wrong direction.
Copyright 2013 Barry Applewhite, Plano, Texas. All rights reserved worldwide. Derived from materials created for Christ Fellowship, McKinney, Texas. Used by permission.
 David E. Garland, 1 Corinthians, Baker Exegetical Commentary on the New Testament (Grand Rapids: Baker Academic, 2003)428-29.
 Anthony Thiselton, The First Epistle to the Corinthians, New International Greek Testament Commentary (Grand Rapids: William. B. Eerdmans publishing Company, 2000)702, quoting R.B. Hays.