There are so many verses that illustrate God's divine choice.I've never heard of the concept that Israel as a nation was elect. Is there a passage for that?
Spiritual Israel in Christ is elect. The house of Israel in Christ is elect. I can't find a single passage that states "the nation of Israel" would be elect.
Deuteronomy 7:6
For you are a holy people to the Lord your God; the Lord your God has chosen you to be a people for His personal possession out of all the peoples who are on the face of the earth.
To be chosen by God is the same as being God's elect.
Did God choose the nation of Israel or not?