If God has forgiven ‘everyone’, does that not mean that everyone should be going to heaven? If they are no longer debtors than on what basis are they being punished? Did Christ pay for the sins of many in vain?
God hasn’t forgiven everyone. The premise of your question is wrong.
If God could just forgive everyone, then Christ would have never needed to die. But God can’t forgive arbitrarily; He is the Perfect Judge and sin must pay its price – death.
Christ died for all, and His shed blood is sufficient to save all. But all people were not automatically saved just because Jesus died. Jesus made salvation possible for all those who turn to Him in belief, repentance and obedience (because true belief will naturally be followed by repentance and obedience).
The idea that all are saved, rather than those who have turned to God on HIS TERMS, is called “universalism”.
On what basis is a person condemned or punished? On the basis that all have sinned (Rom 3.23). People die and go to hell because they have violated God’s holiness by breaking His Law.
A person can go to Heaven because they realize their lost and hopeless dilemma, and turn in repentant, obedient response to God in the way that God has determined results in salvation.