New Life in Christ
Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new. (2 Corinthians 5:17)

There is a difference between a new car and an old derelict immobile car that hasn't been used for several years. What makes an old dead car different from a new car? - The engine, the chassis, and other internal furnishings.
In like manner, what does 2 Corinthian 5 verse 17 means? Specifically what does it mean;
To be in Christ?
Be a new creature (in Christ)?
For old things to be passed away?
All things are become new?
1. What Does It Mean to Be In Christ?
It means to be born-again β The New Birth.
"Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God." (John 3:3)
"For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life." (John 3:16)
This new birth comes via repentance, turning away from sins, and turning to the Lord.Β
Apostle Paul wrote, "Testifying both to the Jews, and also to the Greeks, repentance toward God, and faith toward our Lord Jesus Christ." (Acts 20:21)
Repentance is not changing morals or turning a new leaf. A penitent soul recognizes that he has sinned against a just and holy God. The repentant soul acts like the prodigal son, returning to the father for pardon, forgiveness, reconciliation, and fellowship.
Our sins caused a separation between us and God. When we acknowledge our sins and return to God through our Lord Jesus, God will forgive us and make us one of His own.
"Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me." (John 14.6)
2. New Creature in Christ
One who has truly repented will have a change of heart and attitude towards sin β never to go back. Β However, just as no one ever gets birthed by oneself, this new life is an act of God's grace by which God works in the human heart to effect a total transformation.
12 But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name: 13 Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God. (John 1:12-13) Β
No one can save us but God. God is the source by which the new birth is given (v. 13), but free will is the means by which it is βreceivedβ (v. 12). It is βbyβ grace but βthroughβ faith that we are saved (Eph. 2:8).
3. Old Things are Passed Away
A truly born-again Christian experiences a radical transformation internally and externally. This experience comes with the joy of salvation. The child of God can boldly sing.
There's a great change since I'm born again.
There's a great change since I'm born again
There's a great change since I'm born again
There's a great change since I'm born again
Through God's enabling grace and power, old sinful desires, affections, and lusts are mortified (killed). New creatures in Christ disassociate from sinner friends, lifestyles, and practices that will hold them back from their heavenward focus.
A pastor exposition best explains this experience as follows.
"If I go to a sinner and say, βI am exactly the same as you, the only difference is that I have a Savior,β but I do all the same things he does β I tell the same dirty jokes he tells and I waste my time the same way he does and I do everything he does β and then I say, βI have a Savior, you ought to have a Savior,β doesnβt he have the right to ask me what kind of Savior I have?
What profit is there for a man to say, βI have a physicianβ if he is dying on a cot? What does it profit a man to say, βI have a Saviorβ if he is living in iniquity?
Source: Β©A. W. Tozer, Reclaiming Christianity - A Call to Authentic Faith
4. All Things Become New
Both at the instance of salvation and as the Christian continues to grow in God's grace, all things continue to become new.
This newness of life is not the work of human effort or self-discipline. After a person is regenerated into a new creature, his old value systems, priorities, plans, and beliefs are gone.
12 Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling. 13 For it is God which worketh in you both to will and to do of his good pleasure. (Philippians 2:12-13)
Through the blood of Jesus Christ, the hold, sway, and power of sins over the regenerated Christianβs life is broken. Through Godβs grace, Christians now have the power to live victoriously over sin, temptation, Satan, and the world. This is what is meant by living in holiness.
As regenerated souls β new creations in Christ, God not only commands us to walk and live in holiness, but also gives us the divine enablement to so live
13 For if the blood of bulls and of goats, and the ashes of an heifer sprinkling the unclean, sanctifieth to the purifying of the flesh: 14 How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God? (Hebrews 9:13-14)
As we continue to walk in the light of Godβs word and avail ourselves of the means of grace, God will give us victory every day.
12 But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name. (John 1:12)
7 But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin. (1 John 1:7)