Replies

Here's is a commentary which might help you to understand the section from Romas 11 from which you lifted a single passage:

Matthew Henry's Concise Commentary
11:11-21 The gospel is the greatest riches of every place where it is. As therefore the righteous rejection of the unbelieving Jews, was the occasion of so large a multitude of the Gentiles being reconciled to God, and at peace with him; the future receiving of the Jews into the church would be such a change, as would resemble a general resurrection of the dead in sin to a life of righteousness. Abraham was as the root of the church. The Jews continued branches of this tree till, as a nation, they rejected the Messiah; after that, their relation to Abraham and to God was, as it were, cut off. The Gentiles were grafted into this tree in their room; being admitted into the church of God.
Multitudes were made heirs of Abraham's faith, holiness and blessedness. It is the natural state of every one of us, to be wild by nature. Conversion is as the grafting in of wild branches into the good olive. The wild olive was often ingrafted into the fruitful one when it began to decay, and this not only brought forth fruit, but caused the decaying olive to revive and flourish.
The Gentiles, of free grace, had been grafted in to share advantages. They ought therefore to beware of self-confidence, and every kind of pride or ambition; lest, having only a dead faith, and an empty profession, they should turn from God, and forfeit their privileges. If we stand at all, it is by faith; we are guilty and helpless in ourselves, and are to be humble, watchful, afraid of self-deception, or of being overcome by temptation. Not only are we at first justified by faith, but kept to the end in that justified state by faith only; yet, by a faith which is not alone, but which worketh by love to God and man.

Just remember please that when God says NO MAN can take the Saved from His hands, that includes any man confessing The Lord Jesus, that includes you and me if we have the simple profession found in John 3:16 and echoed in Matthew 16:16 by Peter, and in the House of Cornelius, and by Paul everywhere on his mission trips, and most importantly by Jesus speaking to those of the scribes and Pharisees who asked Him what is the work of God that they must do to be saved (Believe on Him Whom He has sent)..