Let me color code that verse to see what goes with what.
Romans 11:7 What then? Israel [as a whole] hath not obtained that which he seeketh for; but the election [the remnant] hath obtained it, and the rest [all but the remnant] were blinded
Only a portion of Israel was blinded, the believing remnant was not.
Verses 1-4 tell of how Elijah complained that all Israel had stumbled except for him, and God says "Nah, I have a remnant of believers within Israel".
And verse 5 says that just as there was a remnant by grace back then, there is also a remnant by grace today.
The believing remnant back then and now were both by grace.
Thank you, that helped immensely.
Now to address the issue of the kind of grace that was available before Christ came.
I submit it was not a fullness of Grace like we have now.
John 1:17 For the law was given by Moses, but grace and truth came by Jesus Christ.
I'm saying that no one has ever been saved into eternal life except by grace.
Just as Paul tells us that faithful Abraham was justified by faith apart from works back in his day just as the faithful are today.
You can demonstrate your faith with works, but it is your faith that saves, not the demonstration.
Yes, he was justified by faith, but he was not indwelt by the Holy Spirit. The OT saints were looking for this day to come.
1 Peter 1:10 Of which salvation the prophets have enquired and searched diligently, who prophesied of the grace that should come unto you:
Then, of course, this must be considered a work....burnt offering and sacrifice. And circumcision.
Genesis 22
And it came to pass after these things, that God did tempt
Abraham, and said unto him,
Abraham: and he said, Behold, here I am. And he said, Take now thy son, thine only son Isaac, whom thou lovest, and get thee into the land of Moriah; and offer him there for a burnt offering upon one of the mountains which I will tell thee of. And
Abraham rose up early in the morning, and saddled his ass, and took two of his young men with him, and Isaac his son, and clave the wood for the burnt offering, and rose up, and went unto the place of which God had told him. ...
But when it comes to the earthly kingdom promised to Israel, works are involved to remain in that earthy kingdom.
But that is an earthly kingdom, not eternal life (ie. not salvation).
You can be kicked out and brought back in to that kingdom.
You can't be kicked out of the body of Christ which is all faithful believers.