What does Romans 11:20 mean?

Paul has warned the Gentile Christians not to be arrogant toward the Jewish people. Though Israel had rejected faith in Christ as the way to be right with God, Gentile Christians are in no way superior or favored to the Jews. Paul has compared those Israelites to unproductive branches broken from a tree. Purely for the sake of this point, those people are like limbs deliberately pruned to make way for the new branches to be added: those new branches are the Gentiles.

That fact, Paul now writes, should cause a Gentile Christian to be even more humble about their place on that symbolic tree. The only difference between the broken off branches and the newly added branches is faith in Christ. Paul warns the Gentile Christians to hold tight to the branch by continuing in their faith in Christ.

Lest we lose sight of Paul's point here, this is not a suggestion that saved believers can lose their salvation. The analogy of branches and trees, so far as this specific statement goes, extends only to the idea that God has the right to add or remove branches. Since God removed Israel for their stubbornness and pride, He is more than able to do the same to Gentiles for their arrogance.

Instead of pride in their position, these non-Jewish believers should respect the consequences of drifting from the very faith that brought them to the tree in the first place (Hebrews 2:1). Instead of false confidence in themselves because of their position, the Gentile believers should fear the God who gave them that spot and took it away from the unbelieving Jewish people of their era.