When Jesus came, at that point all were spiritually dead in Adam. He represented not only the Jewish people but all mankind, taking away the sins of the world (Greek kosmos) through His death and resurrection. When He went into the grave, we went with him, as He overcame sin (lost identity) and death. In John 14 Jesus speaks of ‘preparing a place’ which refers to preparation for a marriage relationship (and is not about going to heaven to build mansions for us) so that we can be in Him and He in us.
“On that day you will know that I am in My Father, and you are in Me, and I in you.” John 14:20).
The cross and the resurrection, coupled with the Holy Spirit’s coming, marked the birth from above for all mankind: the new creation – the one new man in Christ, where there is no distinction between Jew and Gentile. The gospel is announcing that Jesus, through His death, overcame sin (our lost identity) and death, bringing life and immortality. The good news is the reconciliation of the entire cosmos to God, where all sins are forgiven and death loses its sting. This reconciliation, described in Colossians, encompasses all things through the blood of the cross.
…that God was reconciling the world to himself in Christ, not counting people’s sins against them. And he has committed to us the message of reconciliation (2 Corinthians 5:19).
For God was pleased to have all his fullness dwell in him, and through him to reconcile to himself all things, whether things on earth or things in heaven, by making peace through his blood, shed on the cross (Colossians 1:19-20).