Matthew 3:8

Bring forth therefore fruit worthy of repentance: and think not to say within yourselves, We have Abraham to our father: for I say unto you that God is able of these stones to raise up children unto Abraham.

Fruit worthy of repentance ... suggests the true relationship between repentance and reformation of life. Reformation of life is not repentance but issues forth from repentance and is a direct result or "fruit" of repentance. That repentance cannot be reformation of life is seen in the words of Christ who allowed that it is possible to repent many times in one day (Luke 17:4), a thing that cannot be understood of reformation.

Think not to say ... Here Christ answered an alibi and destroyed a refuge of these ancient sinners. They supposed themselves safe because they were the seed of Abraham to whom the promises of old had been truly certified. However, in this place John blasts their complacency and opens the door for the "spiritual sons" of Abraham (Galatians 3:26-29). Here in the preaching of John the Baptist was the beginning of that truth so fully expounded by Paul in which it appears that "He is not a Jew who is one outwardly ...." (Romans 2:28,29).