1 Corinthians 6:17 KJV — But he that is joined unto the Lord is one spirit.
This is the reason for 2 Corinthians 5:17…because you and the Lord are now one spirit.
Remember: the real you is a spirit, who has a soul (mind+will+emotions), and lives in a body.
His presence displaces everything it encounters. The light dispels the darkness. The hills melt like wax at the presence of the Lord. The new subsumes the old.
The old is gone. Fact.
All that’s left is for you to actually believe this and let what this truth that you believe be the cornerstone of everything you do.