Traditional religious sanctions are ineffective and implausible. If fear of imaginary judges, imaginary rewards, imaginary punishments were effective sanctions, then crime rates would be lower in devout countries than in sceptical and secular ones. Yet crime rates are many times higher in Catholic Latin America, where belief in judgement in the afterlife is strong, than in Japan, where it is virtually absent. God's merciful and forgiving character in the three Western religions is a weakening of the sanctions. If you truly and deeply repent of your sins, God will forgive them and remit your eternal punishment.
Sin is wiped out once it is repented.
So it is easy to commit sin, knowing that it can be forgiven. Finally, sanctions are only effective if they are credible. The problem with rewards and punishment in the afterlife is that they happen after death, and there are no witnesses who report back to the living. No-one has returned from heaven or hell to tell us if these places exist, or if the punishments and rewards there fit the deeds. There have been no studies of people claiming to be reincarnated, to check whether each new incarnation corresponds to the merits of the previous life.