If God is merciful, why not just sin?

Because God’s mercy is not a licence to sin. Forgiveness is for the one who regrets his mistake and mends his ways, not for the one who deliberately counts on it.

This question is best understood by thinking of parents and their children. Good parents love their child and forgive a great deal. But no sensible child would say, my mother will forgive me anyway, so I will deliberately break everything. A child who thinks like that has not understood his parents’ love. God’s mercy is even greater than a mother’s love, but it is not a blank cheque.

The Holy Qur’an says clearly to whom forgiveness applies. It applies to the one who makes a mistake out of ignorance or weakness and soon regrets it. Whoever deliberately keeps on doing evil and only wants to turn back at the last moment cannot count on it. So whoever sins in order to give God a chance to be gracious turns repentance into a game. True repentance means no longer wanting what is wrong.

On top of that, many wrongs carry their consequences within themselves. God has ordered the world by cause and effect. Whoever lives against this order often feels the consequences already in this life, in his health, in his family or in society. This is not arbitrary. It is a protection that calls a person back.

Finally, according to the Holy Qur’an, forgiveness is only good when it leads to reform. Leniency without any limit would encourage crime and violate the rights of the innocent who suffer from injustice. A judge who let every offender walk free at once would not be merciful but unjust towards the victims. God’s mercy is perfect precisely because it is also just.