By that I mean his death is the ground of salvation that takes away God's wrath and gains God's favor. Nothing else in the whole universe can do that. This tells us that with the shedding of blood there is remission. In other words whoever Christ died for he succeeded in actually paying for, and remitting their sin. Let us look specifically at imputation.
Imputation is real, in that it really works.
The word impute simply means to transfer to one's account. Christ had the sin of the Elect, and theirs alone, imputed from their account to Christ's account when he hung on the cross. If he had everyone's sin imputed to him, then everyone would be saved, because their sins would be remitted by Christ's blood shed. His blood is his whole merit that includes his life as well as his death. To say that Christ died for everyone to render them potentially savable, because 'Christ has done all he can do and the rest is up to you,' is a lie that defiles the very name of God.