What is the new creation?

“If anyone be in Christ, he is a new creature” (AV).
It has seemed self-evident that we were being promised here, overlapping with the language of a new birth (John 3:5-6), a metaphysical or ontological transformation of the individual person.
As the italics in the AV indicate, the words ‘he is’ are not in the original text...
A shortcoming of this interpretation of ‘the new creature’ as transformed individual personality is that the word ‘ktisis’, here translated ‘creature’ or ‘creation’, is not used elsewhere in the New Testament to designate the individual person. It is most often used to designate not the object of creation but rather the act of creating (e.g. Romans 1:20)...
In the one other place where the phrase ‘new creation’ is used, it is quite parallel to the ‘new humanity’ of Ephesians 2:15, not a renewed individual but a new social reality, marked by the overcoming of the Jew/Greek barrier; ‘neither circumcision nor uncircumcision but a new creation’ (Galatians 6:15).
Putting together these strictly linguistic observations...we should lean to the kind of translation favoured by the more recent translators; literally, ‘if anyone is in Christ, new is creation,’ or more smoothly, ‘there is a whole new world’ (NEB).
The accent lies not on transforming the ontology of the person...but on transforming the perspective of one who has accepted Christ as life context.
This is certainly the point of the rest of the passage in question.
Paul is explaining why he no longer regards anyone from the human point of view; why he does not regard Jew as Jew or Greek as Greek, but rather looks at every person in the light of the new world which begins in Christ. ‘The old has passed away, behold the new has come’ is a social or historical statement, not an introspective or emotional one.
from ‘The Politics of Jesus’ John Howard Yoder - 2nd Edition 1994
pgs. 221-223

Forgive me this extended quotation, but it highlights in broad strokes the impact ‘individualism’ has had on the modern evangelical church.
It is by no means all bad. Many evangelicals, me included, have been drawn to Christ with the promise of a complete makeover...as though the thing being made over is ‘me’.
But therein lies its fatal flaw.
A ‘me’ centric new creation has spawned multitudes of Christian ‘shut-ins’ even when we are in fellowship with one another. There is no ‘body politic’, no social
ethic defining us as God’s ‘new social entity’ in the world.
As long as we understand the ‘new creation’ as the new ‘me’ or the new ‘you’, our engagement with the world is scattershot - a helter-skelter mixture of pious platitudes and self-branded spirituality.
This would be understandable if Jesus had left us with no definitive economic policy, if he had limited sin to the personal realm, if he had said nothing about the pitfalls of wealth and possessions, if he had said nothing about the sword and making peace.
But he did leave us with those things and it is evident through the book of Acts that the early church ‘got it’ - from ‘selling their possessions and goods and giving to everyone in need (Acts 2:45) to food distribution to widows (Acts 6) to not resorting to the sword when confronted by mortal enemies (Acts 7) etc.
But somewhere in the generations since, the 'new creation', a very social and visible reality has been scaled down to the very private internal reality of 'what I believe in my heart'.
The impact of individualism on the contemporary church has been to disable what is the real ‘new creation’ in this world, the body of Christ.
Again this would be understandable if we were meant to understand the body of Christ as some theological construct overarching those who believe Jesus to be ‘their personal Saviour’.
But he has left us with much more: the hearing of God’s word and putting it into practice - an undeniable and severe social responsibility we are incapable of doing except as members together of his body.