Rom 11:2-5, Isa 6:13, Joel 2:32, Mic 2:12-13, Jer 23:3-6

In the Old Testament, God told Elijah, who felt his life was threatened, that there were seven thousand remaining in Israel who did not bow their knees to Baal. (1 Kings 19:10,18)

1 Kings 19:10 And he said, I have been very jealous for the Lord God of hosts: for the children of Israel have forsaken thy covenant, thrown down thine altars, and slain thy prophets with the sword; and I, even I only, am left; and they seek my life, to take it away. 18 et I have left me seven thousand in Israel, all the knees which have not bowed unto Baal, and every mouth which hath not kissed him.

In the Old Testament, it was prophesied that some of the remnant would be called by God. (Joel 2:32, Mic 2:12-13)

Joel 2:32 And it shall come to pass, that whosoever shall call on the name of the Lord shall be delivered: for in mount Zion and in Jerusalem shall be deliverance, as the Lord hath said, and in the remnant whom the Lord shall call.

Mic 2:12 I will surely assemble, O Jacob, all of thee; I will surely gather the remnant of Israel; I will put them together as the sheep of Bozrah, as the flock in the midst of their fold: they shall make great noise by reason of the multitude of men. 13 The breaker is come up before them: they have broken up, and have passed through the gate, and are gone out by it: and their king shall pass before them, and the Lord on the head of them.

In the Old Testament, it was foretold that Christ would lead and save those whom God had left behind. (Jeremiah 23:3-6)

Jeremiah 23:3 And I will gather the remnant of my flock out of all countries whither I have driven them, and will bring them again to their folds; and they shall be fruitful and increase. 4 And I will set up shepherds over them which shall feed them: and they shall fear no more, nor be dismayed, neither shall they be lacking, saith the Lord. 5 Behold, the days come, saith the Lord, that I will raise unto David a righteous Branch, and a King shall reign and prosper, and shall execute judgment and justice in the earth. 6 In his days Judah shall be saved, and Israel shall dwell safely: and this is his name whereby he shall be called, The Lord Our Righteousness.

In the Old Testament, God promised to leave holy seeds. (Isa 6:13)

Isa 6:13 But yet in it shall be a tenth, and it shall return, and shall be eaten: as a teil tree, and as an oak, whose substance is in them, when they cast their leaves: so the holy seed shall be the substance thereof.

Just as God left Elijah a remnant of 7,000 who did not bow the knee to Baal, so God left behind such people in this age as well. (Romans 11:2-5)

Romans 11:2 God hath not cast away his people which he foreknew. Wot ye not what the scripture saith of Elias? how he maketh intercession to God against Israel saying, 3 Lord, they have killed thy prophets, and digged down thine altars; and I am left alone, and they seek my life. 4 But what saith the answer of God unto him? I have reserved to myself seven thousand men, who have not bowed the knee to the image of Baal. 5 Even so then at this present time also there is a remnant according to the election of grace.