What if someone has a million bad deeds and a million and one good deeds; would he enter Paradise despite his bad deeds and mistakes, and where is the justice in that?

Sins between a servant and his Lord are subject to hope for forgiveness. As for the rights of people, they must be fulfilled on the Day of Resurrection. So, whoever has wronged his brother should seek his forgiveness before his good deeds are taken from him. If he has no good deeds, then some of his brother's evil deeds will be taken and cast upon him.

As for the rights of Allah the Almighty, He overlooks them for whomever He wills, out of grace and mercy. If He holds a servant accountable for his evil deeds, that is His justice and wisdom. If He forgives him, that is His grace and mercy. Allah is not questioned about what He does due to the perfection of His wisdom. If Allah were to punish people for what they earned, He would destroy them all. And whoever pardons his right deserves praise, and Allah is most deserving of all good. One should not believe that he will be saved by his deeds, for the only reliance is the mercy of Allah the Almighty.