Is it unfair that God turns bad deeds into good ones after sincere repentance?

No. The path of repentance is equally open to every person. If some take it and others do not, it is not God who treats people unequally, but people who treat themselves unequally.

At first the question sounds reasonable. Someone has done a great deal of wrong, repents sincerely, and God turns his bad deeds into good ones. Does he not then have an advantage over others who have tried hard all their lives?

What matters is who takes the first step. Repentance begins with the person himself. He must turn to God and ask for forgiveness. This opportunity is not reserved for one particular group. It is open to every person at every moment. The hadith above describes it with a beautiful image. God stretches out His hand at night for the one who sinned during the day, and during the day for the one who sinned at night.

So whoever envies another for being forgiven need not envy him. He can take the same path himself. No one is prevented from doing so. Even someone who considers himself a good person has faults he can repent of, and the same promise applies to him.

The inequality therefore does not come from God. People treat themselves unequally. One uses the open door, another walks past it. God responds to each person according to the choice that person makes.

Moreover, true repentance is no small matter. The verse above links it with faith and good deeds. Whoever turns back in this way changes his whole life. That God rewards such a turning generously is not injustice but an expression of His mercy.