The evidence of authentic transformation by Christ is:
Galatians 5:22-23
"22 But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, 23 gentleness, self-control; against such things there is no law."
Claiming to be a Christian, even deciding to be one because it seems like a better life is not transformation its only play-acting to feel safe and to be accepted by others.
This false Christianity is not sustainable. As soon as a person like this is hit with difficulties or are confronted with their sin, the rage and anger emerge without one thought to seeking God to discover their flaws for cleansing. When rage and anger are the first response of anyone over a challenge we know this person harbors it just under the surface waiting for an excuse to present itself.
Those who have been transformed by Christ want to be changed, they want to be confronted about their sin and will go to prayer if the accusation is true. If they find themselves to have failed or sinned they want to correct themselves and begin again obeying Christ.
Remember that God does not "reform" the sinner, He transforms them.
2 Corinthians 3:18
"And we all, who with unveiled faces contemplate the Lord’s glory, are being transformed into his image with ever-increasing glory, which comes from the Lord, who is the Spirit.
The word "reform" seems to imply there was once righteousness, it went away and is returned.
The word "transform" means to be made completely different, changed permanently never to return to the old ways or thinking again.
2 Corinthians 5:16-18 "…16 So from now on we regard no one according to the flesh. Although we once regarded Christ in this way, we do so no longer. 17 Therefore if anyone is in Christ, he is a new creation. The old has passed away. Behold, the new has come! 18 All this is from God, who reconciled us to Himself through Christ and gave us the ministry of reconciliation:…"
Joel 2:13
"Rend your heart
and not your garments.
Return to the Lord your God,
for he is gracious and compassionate,
slow to anger and abounding in love,
and he relents from sending calamity."
Ask yourself; "Have I been transformed by Christ" or "am I a pretender."