Octoberose, the thought of explaining the remnant class first seems like a huge task to me. I first learned of the salvation of all, and everything fell into place afterward, but each situation is different, and anything is possible with God. Im, hoping to learn something more on this subject from others.
I would suggest Romans 11. It talks of the remnant of Israel and the engrafting of the gentiles, which clearly speaks to the grace of God.
Romans 11:5–7
5 In the same way then, there has also come to be at the present time a remnant according to God’s gracious choice.
6 But if it is by grace, it is no longer on the basis of works, otherwise grace is no longer grace.
7 What then? What Israel is seeking, it has not obtained, but those who were chosen obtained it, and the rest were hardened;
One thing that dictates how I approach anything involving God, when talking to someone, is love. "God is love", first and foremost, it's the very essence of who he is. everything he does is goverend by that truth. His just and righteous plan for the salvation of all mankind is a witness to that truth. I was myself, greatly influenced by first knowing this, and everything fell into place afterward.
The following scriptures made me question what I thought I knew, maybe they'll help in your situation. If not, I can share other scripture about the remnant class.
Psalm 66:4,
4 All the earth will worship Thee, and will sing praises to Thee; they will sing praises to Thy name. Selah.
Psalm 67 is magnificent as well:
1 God be gracious to us and bless us, and cause His face to shine upon us-Selah. 2That Thy way may be known on the earth, Thy salvation among all nations. 3 Let the peoples praise Thee, O God; let ALL the peoples praise Thee. 4 Let the nations be glad and sing for joy; for Thou wilt judge the peoples with uprightness, and guide the nations on the earth. Selah. 5Let the peoples praise Thee, O God; let all the peoples praise Thee. 6 The earth has yielded its produce; God, our God, blesses us. 7 God blesses us, [in order] thatall the ends of the earth may fear Him.
Psalm 72:11-19
11 And let all kings bow down before him, All nations serve him. . .17 May His Name endure forever; May His Name increase as long as the sunshines; And letmen bless themselves by Him; Let all nations call him blessed. . .18Blessed be the LORD God, the God of Israel, Who alone works wonders. 19 And blessed be His glorious name forever; And may the whole earth be filled with His glory. Amen, and Amen.
Psalm 86:9 and 10
9 All nations whom Thou hast made shall come and worship before Thee, O Lord; and they shall glorify Thy name. 10 For Thou art great and doest wondrous deeds; Thou alone art God.
When God's Kingdom fills the whole earth like the great mountain range foretold by the prophet Daniel (2:35). Isaiah foresaw this day as well when he wrote in Isaiah 2:2-4,
2 Now it will come about that in the last days, the mountain of the house of the LORD will be established as the chief of the mountains [i.e., nations], and will be raised above the hills; and all the nations will stream to it. 3And many peoples will come and say, "Come, let us go up to the mountain of the LORD, to the house of the God of Jacob; that He may teach us concerning His ways, and that we may walk in His paths." For the law will go forth from Zion, and the word of the LORD from Jerusalem. 4 And He will judge between the nations, and will render decisions for many peoples; and they will hammer their swords into plowshares, and their spears into pruning hooks. Nation will not lift up sword against nation, and never again will they learn war.