Then how can a Just God demand a double payment ?
That's an interesting example to use. Think about the sacrifice it replaced. If an acceptable lamb was sacrificed and you failed to eat it what happened? If an acceptable lamb was sacrificed and you failed to apply the blood to the door - what happened to your firstborn?
The existence of a sacrifice without the application of the sacrifice to the sin/person is without effect.
No further payment is required. But that doesn't mean you turned in the ticket - or even picket it up at the "will call" window.
BINGO..Give the man a cupie doll.
The fact is that Christ could not have then died for the sin of ALL men..because if He did then all men would have to be saved (as God is just and would never demand double payment for some)
The fact is that the atonement (as in the example you gave ) is LIMITED
It is limited to those that repent and believe .