Notice once more, that it is a present forgiveness. It does not say I am he that will blot out thy transgressions, but that blotteth them out now. There are some who believe, or at least seem to imagine, that it is not possible to know whether our sins are forgiven in this life. We may have hope, it is thought, that at last there will be a balance to strike on our side. But this will not satisfy the poor soul who is really seeking pardon, and is anxious to find it; and God has therefore blessedly told us, that he blotteth out our sin now; that he will do it at any moment the sinner believes. As soon as he trusts in his crucified God, all his sins are forgiven, whether past, present, or to come. Even supposing that he is yet to commit them, they are all pardoned. If I live eighty years after I receive pardon, doubtless I shall fall into many errors, but the one pardon will avail for them as well as for the past. Jesus Christ bore our punishment, and God will never require at my hands the fulfilment of that law which Christ has honored in my stead; for then would there be injustice in heaven: and that be far from God. It is no more possible for a pardoned man to be lost than for Christ to be lost, because Christ is the sinner’s surety. Jehovah will never require my debt to be paid twice. Let none impute injustice to the God of the whole earth: let none suppose that he will twice exact the penalty of one sin. If you have been the chief of sinners, you may have the chief of sinner’s forgiveness, and God can bestow it now.
From the Metropolitan Tabernacle Pulpit, Volume 1, Sermon 24 by Charles Haddon Spurgeon