Romans 11

13 Paul was appointed by Jesus to minister to the Gentiles and the Jews (Acts 9:15). He preached directly to both, but often found that the Jews rejected the Good News from God. The Gentiles turned out to be more eager to accept the Jewish Messiah. Thus, Paul preaches indirectly to the Jews through the faithfulness of the Gentiles.
14 Paul hopes that when the Jews see how much the Gentiles have benefited from Jesus, they will accept Jesus as well.

Paul considers all Jews his family, and it is right to want your family to know God.

15 God has always wanted all people to be reconciled to Him. He specially appointed the Israelites to keep His Law, carry out His judgements, and tell the world about Him. However, most of the remaining Israelites (the Jews) rejected their Messiah, who was the fulfillment of the Law and judgements of God. God then greatly expanded the ministry among the Gentiles, who were more responsive. Thus, some people from every "tribe and language" will be reconciled to God (Rev 5:9).

It appears there will be a day when a great revival occurs in Israel (Rom 11:26). This may signal that the End, when the dead will rise again, is near.

The overall point is that the "rejection" of the Jews has opened the doors for reconciliation of the Gentiles to God. Everyone will benefit all the more when Israel accepts its Messiah.

16 Holiness can only come from holiness. Jesus is the firstfruit among men. Thus, all who are a part of Jesus through faith share His holiness. Jesus is also the foundation and nourishment for God's people. Thus, all who depend on Him share His holiness.
17 Whether the Israelites acknowledged it or not, their foundation has always been Jesus, who is God. When they rejected their Messiah, they became unfruitful and were pruned out of their own tree (spiritually speaking). The Gentiles, who had fewer advantages, were found faithful and were grafted in where the intended branches failed to grow.
18 Pride is not supposed to be part of the Christian's personality. Sometimes we can be tempted to do so. However, we must remember that there is nothing special about a Christian that makes him more deserving of salvation than anyone else is. The only advantage we have is that we admit that we need to depend on God completely.
19 Christians should be saddened by the unbelief of others. It is not something we can be happy about beyond the knowledge that the Jew's unbelief benefited the Gentiles. It might also be worthy to note that if the Jews had been faithful they would have eventually ministered to the Gentiles anyway.
20 God accepts anyone who will trust Him and He rejects those without faith in Him.
21 The descendents of Israel who were not faithful to God were rejected. In the same way, the descendents of Christians are not automatically saved. Being from a Christian home or a "Christian" nation has its advantages, but salvation is experienced on an individual level, regardless of the environment.
22 In the same way that a true Christian will never lose faith, the true Christian will never see his relationship with God as an excuse for arrogance. Instead, we should be exceedingly grateful to God, knowing how close we have been to eternal loss.
23 We should also remember that Jews (and anyone else) can be saved during their lifetime. Instead of becoming proud and elitist, Christians should reach out to those who are not saved in the hope that we will all be saved together.
24 God still considers the descendents of Israel special. If a Jew will turn to Jesus, he will be accepted even more gladly.
25 Paul does not want the Gentiles to think they are wiser because they accepted the Jewish Messiah when the Jews did not. God is reaching out to the Gentiles during this time. When "enough" Gentiles are saved (perhaps at least one from every tribe and language), God will again work among the Israelites.
26 The acceptance of the Messiah will be so prevalent in Israel that it will seem that "all" have become Christians.
27 God will keep His promises.
30 Current disobedience does not mean that one will always be disobedient.
33 One of the natural questions might be "Why has God allowed salvation to work out this way?" The answer is that we do not know. We can only know that God knows what He is doing, and His wisdom in all matters is far beyond anything we can comprehend.
34 We do not have the capacity to tell God what is best for us, the world, or the universe.
35 God already "owns" everything, so there is nothing that we can give Him that is not rightfully His anyway. Spiritually speaking, we can not become "good enough" on our own to earn our way to heaven. The whole reason Jesus came to earth was that we are incapable to get to heaven on our own.
36 All things physical and spiritual belong to Him. He made all things, and He made it possible for all to be saved from sin. Thus, every good thing that has ever been or ever will be is from God. Ultimately, all praise and honor belong to God.