The olive tree is native to the eastern coastal areas of the Mediterranean Sea, its fruit is rich in oil and was used since ancient times as food and medication. It is mentioned in the Bible dozens of times: a leaf of the tree was brought by a dove to Noah at the end of the flood, olive oil was used in the lamp of the Tabernacle, its wood was used in the temple by King Solomon, King David went up the slope of the Mount of Olives, weeping, when he fled from his son Absalom, etc. The Lord Jesus used to go frequently to the Mount of Olives in Jerusalem, and there He will step on his return to establish His Kingdom. Two olive trees are mentioned in the book of Revelation to represent two prophets who will witness to Christ in Jerusalem for three and a half years.
In Romans 11:16 -36 the Apostle Paul uses two types of olive tree in an illustration:
1. The cultivated tree, which produces olives: it has a long life, some existing trees are known to have lived for centuries, some for millennia. The tree is highly valued because of its fruit and its wood. In the illustration, the situation of privilege of Abraham and his offspring before God is represented by the cultivated olive tree, which speaks of the "goodness" of God. The Israelites were born and grew up in it, but the nation to a large extent was “hardened”, cut off and thrown away when it rejected Jesus Christ, the promised Messiah, with the exception of a remnant that was converted. But those that were cut off can still be grafted in when they also convert to Christ.
2. The wild tree is useless because the plant does not produce edible fruit. It represents the "severity" of God because of the unbelief in the world (Romans 11:22 -23). The Gentiles, without having the privilege the Israelites were given, are like the branches of this tree. However, if they are saved through faith in Christ, they are like branches grafted into the cultivated tree and thus participate in the "goodness" of God illustrated by its root and sap.
One day, when the "fullness of the Gentiles" is attained, and the whole church of Christ, dead and alive, is caught up to be forever with Him (1 Thessalonians 4:17), this hardening of God which came in part on Israel because of their rejection will cease, and all Israel will be saved (Romans 11:25,26).
At the beginning of Chapter 11 of Romans, Paul asks if God rejected his people (Israel), and immediately gives the emphatic answer: “certainly not”. Abraham was richly blessed by God because of his faithfulness, including his descendants through Isaac and Jacob (later in life called by God “Israel”, which means "you have struggled with God and with men and have prevailed." - Genesis 32:28). If God had rejected Israel, no Israelite could be saved. However, many Israelites are being saved by their faith in Christ, just as the Apostle Paul himself, whose credentials as an Israelite were impeccable. The rejection of the Messiah by Israel was not by all the people, and God has not rejected or abandoned His people.
The fact that Paul refers to Israel as the actual people of God shows that they are still the chosen people of God – it is the people that "He foreknew", i.e. in His foreknowledge. As an example, to Elijah it seemed that of the prophets of the Lord he alone had been left alive, and his life was in imminent danger. But God informed him that He had reserved for Himself seven thousand men who refused to follow the nation that worshipped Baal (1 Kings 19:10-18). There has always been a "remnant" faithful to God, although sometimes small, unlike the Gentiles where apostasy prevails.
The election of grace is the standard according to which the "remnant" exists. Not according to the law of Moses (Chapter 10:4) but on the basis of grace. This remnant existed in the past, exists in the present, and will continue to exist in the future. This is the "Israel of God" in Galatians 6:16. Grace and works are mutually exclusive because what is achieved by works is not by grace. Fortunately the election or choice of God, is by grace and not by works, otherwise no one would reach the necessary conditions to be chosen.
The "remnant" reached justification by grace, having remained faithful to the Lord, but the nation of Israel as a whole did not obtain it because they trusted in their own works and went after other gods, and as a consequence were “hardened” (a kind of spiritual stupor). It is important to note that the distinction is not between Israel and the church of Christ, or between Israelites and Gentiles, but between unbelieving and believing Israelites. The existence of Israelite believers, saved by their faith, is evidence that God has not rejected his people altogether. The hardening of Israelite unbelievers had already been foreseen in the Old Testament (Deuteronomy 29:4, Psalm 69:22,23 and Isaiah 29:10). God would leave them in a state of insensibility to spiritual realities. In Psalm 69:22-23 David described the rejected Saviour asking God to " Let their table become a snare before them, and their well-being a trap..." The table here represents the totality of the privileges and blessings which flow through Christ.
What should have been a blessing was turned into a curse, a sort of deep sleep, a stupor (Isaiah 29:10, 6:9), and apathy, without vision and with bent backs (as slaves carrying large loads on their shoulders). Having refused to recognize the Lord Jesus as Messiah and Saviour, they could no longer see Him. Becoming deaf to His voice, they were suffering from spiritual deafness. This terrible judgement continues today.
Soon comes the second question:"Perhaps they stumbled so that (or so) they should fall?" (Romans 11:11). And again we have the peremptory answer "certainly not". The question refers to the majority of the people who stumbled, and "fall" is a translation of a Greek verb meaning "something complete and irrevocable". It is inconceivable that God might have failed in His faithfulness. They stumbled, but didn't irrevocably fall. If God planned their stumbling, it was so salvation might come to them through the Gentiles: the salvation of the Gentiles would provoke jealousy in the Israelites (Deuteronomy 32:21, Romans 10:19), causing these also to believe in the Messiah because of jealousy of what the Gentile has. So God saves the Gentiles, these in turn announce the Gospel to the unbelieving Israelite, and he ends up believing in Christ seeing the blessings of the Gospel in the lives of the Gentiles.
Today among the people of Israel believers are reduced to a remnant, but in the future there will be a national salvation and that is their "fullness" (verse 12). The stumbling of the Israelites with the decrease of Israel meant wealth for the world and enrichment of the Gentiles (their salvation). Thus, how much more benefit will result from the restoration of Israel before God! When Israel turns to the Lord during the great tribulation, it will become the channel of blessing to the nations and great multitudes will be saved among the Gentiles (Revelation 7:9-14).
Paul extols his Ministry to the Gentiles, for which he had been designed by the Lord Jesus (Acts 9:15), to see if he could somehow provoke the Israelites and save some of them. Verse 15 has the same sense as verse 12, seeing the position of privilege of the world when God put in it the testimony of His people, Israel, the reconciliation of the world with God after the rejection of the Messiah by Israel, and the regeneration, or even resurrection of the world on the admission of the Messiah by Israel in the millennial Kingdom of Christ. But the Gentiles should not despise the Israelites who lost their position of privilege, for as God rejected the unbelieving Israelites and extended His grace to the Gentiles because of their faith, He shall reject the Gentile unbelievers if they don't remain in God. God will yet again accept the Israelites, as a nation, when they leave their unbelief.
Due to its root in Israel, it will be more natural for the nation of Israel to adjust to the Kingdom of God when they believe than for the Gentiles that come from outside. The Body of Christ can never be separated from Christ, who is the Head, nor can a believer be separated from the love of God. But the Gentiles in general may lose the privileged position that they now enjoy, according to Romans 11:22.
In Romans 11:25 Paul reveals a fact that had been hidden until then (a secret, or mystery), lest the readers should be wise in their own opinion: most of the people of Israel will continue in their unbelief “until the fullness of the Gentiles has come in” (i.e. the Church of Christ will be complete and will be taken away to be in His presence), and then all Israel will be saved in the Lord, as prophesied in Isaiah 59:20-21. By "all Israel" we must understand all the Israelites living at that time in the future.
It is impossible to achieve with our human mind the wisdom, righteousness, and the knowledge of God and His judgements and His ways. Nobody can give Him advice, “for of Him and through Him and to Him are all things, to Whom be glory forever. Amen.” (Romans 11:36).