Rom 11:11-14  "So I ask, did they stumble in order that they might fall? By no means! Rather through their trespass salvation has come to the Gentiles, so as to make Israel jealous. Now if their trespass means riches for the world, and if their failure means riches for the Gentiles, how much more will their full inclusion mean!  Now I am speaking to you Gentiles. Inasmuch then as I am an apostle to the Gentiles, I magnify my ministry in order somehow to make my fellow Jews jealous, and thus save some of them." 

The riches of the grace of God are beyond measure and ways are beyond understanding. His grace to those outside of Israel magnifies His love and grace to the world, while providing a means to bring attention to what some in Israel have rejected. His grace in establishing salvation through by grace through faith to non Jewish peoples, is a means to make them jealous and thereby save some of them.
This is important for you to know if you are not Jewish! You Christians who are not of Jewish descent, must be aware, you are not accepted by growing up in a "Christian home" or a so called "Christian country".  No, you must repent and by faith follow after Jesus Christ also. There are no automatic passes because of place or position. 
Don't become arrogant toward others or towards God. The love of God is immeasurable in grace. The wrath of God is immeasurably severe. 

Rom 11:15-22  "For if their rejection means the reconciliation of the world, what will their acceptance mean but life from the dead?  If the dough offered as firstfruits is holy, so is the whole lump, and if the root is holy, so are the branch But if some of the branches were broken off, and you, although a wild olive shoot, were grafted in among the others and now share in the nourishing root of the olive tree,  do not be arrogant toward the branches. If you are, remember it is not you who support the root, but the root that supports you. Then you will say, "Branches were broken off so that I might be grafted in." That is true. They were broken off because of their unbelief, but you stand fast through faith. So do not become proud, but fear. For if God did not spare the natural branches, neither will he spare you.  Note then the kindness and the severity of God: severity toward those who have fallen, but God's kindness to you, provided you continue in his kindness. Otherwise you too will be cut off." 

For both Jews and Non Jews belief is the condition. If anyone turns around and walks from unbelief into belief the grafting back into the tree is established. Jesus is the source of life and love, abide in His Love. 
If you are from Islam, a Roman Catholic, Protestant, Jewish or any heritage that might be named, you can be grafted into the life giving branch of Jesus the Christ, Yeshua Messiah, Isa Al Masih, He is Absolute Love. Believe and receive!

Joh 15:5-10  "I am the vine; you are the branches. Whoever abides in me and I in him, he it is that bears much fruit, for apart from me you can do nothing. If anyone does not abide in me he is thrown away like a branch and withers; and the branches are gathered, thrown into the fire, and burned. If you abide in me, and my words abide in you, ask whatever you wish, and it will be done for you. By this my Father is glorified, that you bear much fruit and so prove to be my disciples. As the Father has loved me, so have I loved you. Abide in my love.  If you keep my commandments, you will abide in my love, just as I have kept my Father's commandments and abide in his love." 


Rom 11:23-27  "And even they, if they do not continue in their unbelief, will be grafted in, for God has the power to graft them in again. For if you were cut from what is by nature a wild olive tree, and grafted, contrary to nature, into a cultivated olive tree, how much more will these, the natural branches, be grafted back into their own olive tree. Lest you be wise in your own sight, I want you  to understand this mystery, brothers: a partial hardening has come upon Israel, until the fullness of the Gentiles has come in.  And in this way all Israel will be saved, as it is written, "The Deliverer will come from Zion, he will banish ungodliness from Jacob"; "and this will be my covenant with them when I take away their sins." 

This is a mystery, we can not know fully the mind of God. He has established His plan, all is as a irrevocable gift, as such. His love and mercy are given freely. None deserve it, none can earn it, all are in the same boat of despair and destruction apart from His marvelous, merciful grace. He is Absolute Love.   

Rom 11:28-32  "As regards the gospel, they are enemies of God for your sake. But as regards election, they are beloved for the sake of their forefathers. For the gifts and the calling of God are irrevocable. For just as you were at one time disobedient to God but now have received mercy because of their disobedience,  so they too have now been disobedient in order that by the mercy shown to you they also may now receive mercy.  For God has consigned all to disobedience, that he may have mercy on all." 

Nothing more can be said; but "Amen" So be it!

Rom 11:33-36  "Oh, the depth of the riches and wisdom and knowledge of God! How unsearchable are his judgments and how inscrutable his ways!  "For who has known the mind of the Lord, or who has been his counselor?"  "Or who has given a gift to him that he might be repaid?"  For from him and through him and to him are all things. To him be glory forever. Amen."