17 Let no one cheat himself, let no one deceive himself. The Lord alone can have mercy. He alone can bestow pardon for sins which have been committed against Himself, who bare our sins, who sorrowed for us, whom God delivered up for our sins. Man cannot be greater than God, nor can a servant remit or forego by his indulgence what has been committed by a greater crime against the Lord, lest to the person lapsed this be moreover added to his sin, if he be ignorant that it is declared, “Cursed is the man that puts his hope in man.” The Lord must be besought. The Lord must be appeased by our atonement, who has said, that him that denies Him He will deny, who alone has received all judgment from His Father. We believe, indeed, that the merits of martyrs and the works of the righteous are of great avail with the Judge; but that will be when the day of judgment shall come; when, after the conclusion of this life and the world, His people shall stand before the tribunal of Christ.
Source: The Treatises of Cyprian (New Advent)