Catholicism and the absolute concept of repentance

The idea that if you believe in that religion and repent, your sins will be forgiven...
Serial killers like Yoo Young-chul and Kang Ho-sun...
They can all be forgiven (if they truly repent).
But Buddhism is just uncompromising ㅡㅡ Retribution.
The concept of the Six Realms of Reincarnation based on karma in this life is both fair and
at the same time, a terrifying religion.
Even if I commit a sin and perform good deeds to wash that sin away, I cannot erase that evil karma and must pay the price for my sins...
If you frame it as "good deeds act as bonus points" as an incentive,
then wouldn't it be an absolute advantage to go with Christianity?