 When Jesus Christ went to the cross to die for his people, to sacrifice for sin, he did all of that. And all that he did is by virtue of a union with them, which was determined by the Father in eternity. Paul says in 1 Corinthians 1 verse 30 that it is of him, of the Father, that you are in Christ Jesus. He did all that he did, Christ, and all that he did, did all that he did by virtue of a union that was determined by the Father in eternity, and what was determined by the Father in eternity was then secured through the incarnate son life and death in history, and then wrought and applied by the Spirit of God when in time that elect one of God is born again, reconciled to God through repentant faith in Christ.