The Fullness of the Gentiles
Concise Bible Dictionary:
This is spoken of in connection with the olive-tree as God’s tree of promise and privilege on the earth. Israel was that tree (Jer.h 11:16); but because of unbelief some (perhaps the most) of the branches were broken off, and some Gentiles were, contrary to nature, grafted into the good olive-tree. But if these Gentiles do not continue in the goodness of God, they also will be broken off, the fullness of the Gentiles will have come in, and Israel will be reinstated (Rom. 11:15-2515For if the casting away of them be the reconciling of the world, what shall the receiving of them be, but life from the dead? 16For if the firstfruit be holy, the lump is also holy: and if the root be holy, so are the branches. 17And if some of the branches be broken off, and thou, being a wild olive tree, wert graffed in among them, and with them partakest of the root and fatness of the olive tree; 18Boast not against the branches. But if thou boast, thou bearest not the root, but the root thee. 19Thou wilt say then, The branches were broken off, that I might be graffed in. 20Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear: 21For if God spared not the natural branches, take heed lest he also spare not thee. 22Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in his goodness: otherwise thou also shalt be cut off. 23And they also, if they abide not still in unbelief, shall be graffed in: for God is able to graff them in again. 24For if thou wert cut out of the olive tree which is wild by nature, and wert graffed contrary to nature into a good olive tree: how much more shall these, which be the natural branches, be graffed into their own olive tree? 25For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in. (Romans 11:15‑25)). It therefore follows that as the admission of the Gentiles to privilege is linked with the failure of Israel, so the taking up of the Jews again for blessing is linked with the apostasy of the Gentiles. A solemn fact for Christendom!
From Anstey’s Doctrinal Definitions:
This expression refers to the full number of elect Gentiles—whom God has chosen to be part of the Church—being saved (Rom. 11:2525For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in. (Romans 11:25)). God is presently conducting an outreach through the gospel in visiting “the Gentiles to take out of them a people for His name” (Acts 15:1414Simeon hath declared how God at the first did visit the Gentiles, to take out of them a people for his name. (Acts 15:14)). When the complete number of Gentiles whom He has chosen believe, the Lord will come and take the Church home to heaven in a glorified state (1 Thess. 4:15-1815For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not prevent them which are asleep. 16For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first: 17Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord. 18Wherefore comfort one another with these words. (1 Thessalonians 4:15‑18)).