Jesus said, “Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God.” In God’s legal system, all of mankind is condemned to hell because we are naturally unable to be holy [“holy” = without sin].  He cannot have sin in His Kingdom.  Makes sense: He is holy!  His choice – because of His nature.  However, He loved us so much that He provided legal forgiveness for any who choose to follow Him.  Quite simple, actually.