To try to state it more clearly:
The church, the body and bride of Christ, has existed since the first sinner believed the promise of Christ in Genesis 3:15. However, the church, the assembly of the firstborn enrolled in heaven, did not gather together as the church until Pentecost. The congregation in the wilderness, the nation of Israel, were not "those sanctified in Christ Jesus, called to be saints," although at least some saints were in their midst.
Are you reading what you are writing? The Israel of God has always been. The OT saints who were, by faith, in Christ Jesus, were as sanctified as you or I.