Romans 11:5 KJV
Even so then at this present time also there is a remnant according to the election of grace.
Paul, speaking of the day in which he lived, the day of grace and the day in which God had set Israel aside to call out of the Gentiles a people for Christ. Even in this day, God had a remnant of Israel reserved for Himself.
I am convinced that in our day the Jew who believes ought to come out of Judaism and align himself or herself with a local church of believers made up of Gentiles of all nationalities, baptized under scriptural authority and united for the purpose of spreading the Gospel of Jesus Christ. I am dubious of so called Messianic Jewish congregations believing the whole concept to be sectarian and contrary to scriptural principles.
And there is a remnant like that; believers of Jewish descent who count that but dung to win Christ and know the power of His resurrection.
Would to God we were blessed to be used of the Lord to persuade some to do just that!