In Romans 11, Paul gives some very deep thoughts using the example of grafting branches into the root of a tree. Though this story, Paul explains that we should not be arrogant towards our other Christian brothers and sisters in other belief systems.
He asked the people if the Jews stumbled so they would ultimately fall, then answered himself, "By no means!" Paul said that through their trespass, salvation has been offered to the Gentiles in order to make Israel jealous!
Paul said that he promoted the Gentiles with higher esteem in order to magnify his ministry with the Gentiles. By doing so, Paul attempted to somehow make his fellow Jews jealous, and hopefully save some of them.
Paul said that if some branches are broken off, and were grafted in among other trees to share a nourishing root, we should not be arrogant towards the branches.
If you are arrogant towards the other branches, remember that you are not the one supporting the root. The root supports you! You may tell yourself that other branches were broken off so that I may be grafted in, but Paul said they were broken off for their unbelief. He said that we should stand fast through faith and not become proud. We should fear God.
Paul pointed out the severity of not supporting one another in Christian love. If God did not spare the natural branches, neither will He spare you! If you do not continue in His Lovingkindness, God will also cut you off!
At the same time, Paul said not to look down upon those in unbelief. If they do not continue in their unbelief, but are grafted back in, God has the power to take them in again. If you were cut from a wild olive tree, grafted to a cultivated olive tree, how much more will the natural trees be accepting of the returning branches to the original tree!
As Christians, we should ask ourselves: Have we became arrogant towards other Christians? Do we look down upon those who do not believe as we do, or do we try to help them join into the Christian faith? Are we showing each other Christian Love? Are we the branches that God would cut off?