For us to understand what Jesus did, we first need to understand the problem of sin.
Sin is referenced as a debt. Remember the Lord's prayer, Matthew 6:12, "And
forgive us our debts, as we also have forgiven our debtors." Some say "sins" instead of debt,
but the point is clear either way. Sin puts us in spiritual debt.
Jesus came to cancel our debt of sin, because the wage of sin as is death and we are unable
to pay that. This is why Jesus calls those who recognize that they are spiritually bankrupt blessed.
He said, "Blessed are the poor in spirit for their's is the Kingdom of Heaven". It is only by realizing
that you are broke spiritually that you will be able to seek Jesus to pay off your debt.
Now when we stand before God in judgement, those who have trusted Jesus as their savior
will have allowed him to cancel their debt of sin and God no longer has to judge them for sin, for
they have accepted the payment that Jesus made for them.
Now Jesus died for everyone, meaning His death was actually an overpayment on sin.
The value of His innocent blood pays for the whole of the worlds sin and more. The problem
is that it is a gift. The debt has been paid for everyone but many do not believe (we are saved by faith)
that Jesus has done this for them, so they don't accept His gift. So when they stand in judgement,
even though their sin debt was paid, they never accepted it in faith so it could be credited to their account.
Its almost like Jesus sends everyone in the world a money transfer to pay of the debt in their bank account
of salvation. Accepting Jesus as saviour is like accepting the funds transfer so the spiritual capitial can be deposited
to our account to pay our debt. Those who don't accept him, in a sense have a pending transaction to their
account to pay of their debt. The funds are send to them from Jesus but they never click the "accept funds" button to accept the funds transfer. So that debt that has already been
paid(through His death on the cross), is never credited to their account because it is a gift and must be accepted. And since now(in this world) is the time to accept Jesus. When they die
and stand before God, it will be too late to say, "I'll accept him now".