We've been seeing that Isaiah's vision of the new creation includes where we are right now. Isaiah speaks of the new heavens and the new earth as a place where people are born â€“ where people die (65:20). John, in the book of Revelation, will make clear that in the final new creation there is no death â€“ and Jesus affirms that there is no marriage in the final new creation!
But at the same time, Paul affirms that if anyone is in Christ, he participates in a new creation.
The New Creation has begun in the ascension of Jesus to the Right Hand of the Father. The New Creation has dawned in the outpouring of the Holy Spirit at Pentecost. That's the "already" of the new creation in Jesus.
The "not yet" is what is still to come â€“ and in between the already and the not yet, we are building â€“ we are enriching and improving â€“ that new creation...