Therefore, if anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new.
old things have passed away meaning all the things you used to do, are used to and known for are gone and a thing of the past.
All things have become new bothers me now...
I just think it means before you knew Christ, all the things you've been through and had done that sticks with you. When in Jesus, they become new.
For an example, dead to sin- you had a tattoo (for personal reason), a dvd player (to watch secular stuff), a car (to drive around serving the world), watch/time (keeping up with worldly affairs), tv (watch what is going on in the world and be brain washed), money (pay for worldly things) etc
but when alive in Jesus-
*the tattoo just becomes a distant memory of the past, it being new represents your testimony as you don't honour or care for the tattoo anymore.
*dvd player- now you can use it for watching Christians related stuff and Godily things
*car- use the car to help your brothers and sisters or to share
*watch/time- use it to keep up with your time to serve God
*tv- use it to know what is going on in the world and how evil is using evil to brainwash people and make evil look good so people can embrace. Also know how people suffer and how you can pray for them
*money- use money to help the poor, share with your brothers and sisters, give to the church
As you can see...I believe this is what the new creation is. Because all the old stuff about you that were used to serve your flesh desire and this world are re-new. New to serve God and his children.