Heavenly Pilgrim said:
There is problem that will not go away. If ones sins were forgiven and paid for on the cross and all is finished as the literal payment would present it, what matters if one believes or not? If the literal payment theory is true, and all is finished, all is finished. Can one’s refusal to accept or refusal to believe undo what is ‘finished’ by God? Can one by his own will’s rejection of a gift, undo what that is represented by the literal payment theory as set in stone never to be changed or altered?
All sins were paid for on the cross, but not forgiven there. Hebrews 2 tells us Christ tasted death for every man, and the wages of sin are death. So all sins were paid for.
But that is a legal thing.
Forgiveness is entirely different. A murderer may be tried and sent to death row and executed. That has nothing to do with whether the victim's family and friends forgive him, or even whether the murderer repented.
God accomplished the legal side of things for us. But the relationship side of things is intensely personal. It is made possible by atonment having been accomplished by Christ. But salvation is something personal, not an automatic thing. It would have been impossible without atonement, but it is not at all the same thing as atonement.