Even so then at this present time also there is a remnant according to the election of grace.
Read Chapter 11
Ambrosiaster
AD 400
Even though many have fallen away, those whom God foreknew have remained in the promise of the law. For those who have accepted Christ as he was promised in the law have remained in the law, but those who rejected Christ have fallen away from it. Commentary on Paul’s Epistles.
The “remnant” refers to the Jews who have believed in Christ. Many of them did believe in the days of the apostles, and even today there are some converts, though very few.
The remnant of the Jews has proclaimed the sign of the Lord to all the Gentiles and has joined to God in one people, drawn to him, the souls of the Gentiles which are brought out of destruction to the knowledge of the Lord.