Replacement theology is a denominational based belief that cannot be supported in the OT or the NT. It not even a debatable issue scripturally speaking.

All who believe in Christ in the church age, both Jew and Gentile, are the Church and the body of Christ.

The nation of Israel in biblical context here refers to the Jews who still reject Christ and are lost. They will enter the tribulation as a nation, still rejecting Christ, living in the Holy land, just as promised by 15-20 different biblical Prophets including Christ Himself.