How does it prove that God is just ...?

Several good answers here...I also saw some misguided thinking as well...God knows our hearts. I am pretty sure that many people we do not even expect to be in heaven will be there. An author once suggested that when we get to heaven we may be surprised to see some we did not expect, yet others absent who we thought would be there. God is the judge, we may see Ghandi there.... Do you think the popes who killed so many righteous people will be there?