Verse 3. All thine iniqities. In this lovely and well-known Psalm, we have great fulness of expression, in reference to the vital subject of redemption. Who forgiveth all thine iniquities. It is not "some" or "many of thine iniquities." This would never do. If so much as the very smallest iniquity, in thought, word, or act, were left unforgiven, we should be just as badly off, just as far from God, just as unfit for heaven, just as exposed to hell, as though the whole weight of our sins were yet upon us. Let the reader ponder this deeply. It does not say, "Who forgiveth thine iniquities previous to conversion." There is no such notion as this in Scripture. When God forgives, he forgives like himself. The source, the channel, the power, and the standard of forgiveness are all divine. When God cancels a man's sins, he does so according to the measure in which Christ bore those sins. Now, Christ not only bore some or many of the believer's sins, he bore them "all, "and, therefore, God forgives "all." God's forgiveness stretches to the length of Christ's atonement; and Christ's atonement stretches to the length of every one of the believer's sins, past, present, and future. "The blood of Jesus Christ his Son cleanseth us from all sin." 1Jo 1:9. "Things New and Old, "1858.
Quoted in The Treasury of David, by Charles Spurgeon. From the additional notes on Psalm 103.