These are the purchase of My blood

Satan knows that those who ask God for pardon and grace will obtain it; therefore he presents their sins before them to discourage them. Against those who are trying to obey God, he is constantly seeking occasion for complaint. Even their best and most acceptable service he seeks to make appear corrupt. By countless devices, the most subtle and the most cruel, he endeavors to secure their condemnation. 

In his own strength, man cannot meet the charges of the enemy. In sin-stained garments, confessing his guilt, he stands before God. But Jesus, our Advocate, presents an effectual plea in behalf of all who by repentance and faith have committed the keeping of their souls to Him. He pleads their cause, and by the mighty arguments of Calvary, vanquishes their accuser. His perfect obedience to God's law has given Him all power in heaven and in earth, and He claims from His Father mercy and reconciliation for guilty man. To the accuser of His people He declares: “The Lord rebuke thee, O Satan. These are the purchase of My blood, brands plucked from the burning.” And to those who rely on Him in faith, He gives the assurance, “Behold, I have caused thine iniquity to pass from thee, and I will clothe thee with change of raiment.” Zechariah 3:4

Satan has an accurate knowledge of the sins that he has tempted God's people to commit, and he urges his accusations against them, declaring, that by their sins they have forfeited divine protection, and claiming that he has the right to destroy them. He pronounces them just as deserving as himself of exclusion from the favor of God. “Are these,” he says, “the people who are to take my place in heaven, and the place of the angels who united with me? They profess to obey the law of God; but have they kept its precepts? Have they not been lovers of self more than lovers of God? Have they not placed their own interests above His service? Have they not loved the things of the world? Look at the sins that have marked their lives. Behold their selfishness, their malice, their hatred of one another. Will God banish me and my angels from His presence, and yet reward those who have been guilty of the same sins? Thou canst not do this, O Lord, in justice. Justice demands that sentence be pronounced against them.”

But while the followers of Christ have sinned, they have not given themselves up to be controlled by the satanic agencies. They have repented of their sins and have sought the Lord in humility and contrition, and the divine Advocate pleads in their behalf. He who has been most abused by their ingratitude, who knows their sin and also their penitence, declares: “The Lord rebuke thee, O Satan. I gave My life for these souls. They are graven upon the palms of My hands. They may have imperfections of character; they may have failed in their endeavors; but they have repented, and I have forgiven and accepted them.”      Prophets and Kings pp. 586-589