I John 2:4 “The one who says, ‘I have come to know Him’ and does not keep His commandments, is a liar, and the truth is not in him.”
You hear scientists rage about finding a new species of this or that. They really aren’t new. It’s just that the scientists didn’t know about them before. They were there all along.
When you become a new creation in Christ, you are new. The old you has passed away. God is not progressively making new creations of believers; believers are those He has already made new creations. Salvation is laying aside “the old self” and putting on “the new self”. You walk different, talk different, even think different, when you become that new creature.
The only reliable evidence of a person being saved is not a past experience of receiving Christ (walking an aisle/ being baptized), but a present life that reflects Christ.
When I look in the mirror, I want to see a genuinely new person. (Not a new more slender body, with a head full of hair even though that would be nice.) I want to see a person that I can look in the eye and say I am a reflection of Christ to the world.