Here’s a beautiful excerpt from Luther’s Galatians commentary on the monster of uncertainty perpetuated by the church in Rome. You can find this excerpt in LW 26:385-388.
I have indicated in a variety of ways that the Christian man must believe for a certainty that he is in a state of divine grace, and that he has the cry of the Holy Spirit in his heart, especially when he is performing his proper function, which is to confess or to suffer for confessing. I did this in order that you might utterly repudiate the wicked idea of the entire kingdom of the pope, the teaching that a Christian man must be uncertain about the grace of God toward him. If this opinion stands, then Christ is completely useless. For whoever doubts the grace of God toward him this way must necessarily doubt the promises of God and therefore the will of God, as well as the birth, suffering, death, and resurrection of Christ.
There is no greater blasphemy against God than to deny the promises of God and God Himself, Christ, etc. Therefore it was the height not only of insanity but of wickedness when the monks were so zealous in enlisting the youth of both sexes in the monasteries for their religious and, as they called them, “holy” orders, as a sure state of salvation; and then, once they were enlisted, they commanded them to doubt the grace of God. Thus the pope also summoned the whole human race to the obedience of the holy Roman Church as a holy estate in which they would be sure to obtain salvation, and then he commanded those who obeyed his laws to have doubts. In this way the kingdom of Antichrist first boasts and exaggerates the sacredness of its laws, orders, and rules, and it promises the certainty of eternal life to those who observe them; but then, when the miserable beings have been punishing their bodies for a long time in accordance with human traditions by keeping vigils, fasting, etc., their reward for all this is not to know whether or not this obedience of theirs is pleasing to God. Satan took a horrible delight in the killing of souls by the papists. Therefore the papacy is a veritable torture chamber of consciences and the very kingdom of the devil.
To prove and support this wicked error of theirs, they used the statement of Solomon in Eccl. 9:1: “The righteous and the wise and their deeds are in the hand of God; whether it is love or hate, man does not know.” Some of them applied this statement to the hate of God in the future, others to that in the present; but neither group understood Solomon, who in this passage is not saying anything like what they imagine.
Moreover, the chief point of all Scripture is that we should not doubt but hope, trust, and believe for a certainty that God is merciful, kind, and patient, that He does not lie and deceive but is faithful and true. He keeps His promises and has now accomplished what He had promised, handing over His only Son into death for our sins, so that everyone who believes in the Son should not perish but have eternal life (John 3:16). Here there can surely be no doubt whether God has been reconciled and is favorably disposed toward us, whether the hate and wrath of God have been removed; for He permits His own Son to die for us sinners. But no matter how much the whole Gospel sets this forth everywhere or how many times it teaches it, this one statement of Solomon, misunderstood at that, was worth more, especially among the devotees and monks of the stricter sort, than all the promises and comfort of all Scripture, yes, than Christ Himself. They abused Scripture for their own destruction, and they received a just punishment for despising the Scriptures and neglecting the Gospel.
It is important for us to know all this. For one thing, the papists are giving the impression today that they have never done anything wrong; therefore they must be convicted on the basis of their own abominations, which they have spread throughout the world, as is attested by their own books, of which an infinite number on this subject still exist. In addition, we can become sure this way that we have the pure and true doctrine of the Gospel—an assurance of which the papacy cannot boast. If everything else were sound there, still this monster of uncertainty is worse than all the other monsters. And although it is obvious that the enemies of Christ teach what is uncertain certain, because they command consciences to be in doubt, still they are so filled with the madness of Satan that in their smugness they condemn and kill us who disagree with them, as though we were the heretics and they were completely certain of their doctrine.
Let us thank God, therefore, that we have been delivered from this monster of uncertainty and that now we can believe for a certainty that the Holy Spirit is crying and issuing that sigh too deep for words in our hearts. And this is our foundation: The Gospel commands us to look, not at our own good deeds or perfection but at God Himself as He promises, and at Christ Himself, the Mediator.
By contrast the pope commands us to look, not at God as He promises, not at Christ our High Priest, but at our own works and merits. From the latter course, doubt and despair necessarily follow; but from the former, certainty and the joy of the Spirit. For I am clinging to God, who cannot lie. He says: “I am giving My own Son into death, so that by His blood He might redeem you from sin and death.” Here I cannot have any doubts, unless I want to deny God altogether. And this is the reason why our theology is certain: it snatches us away from ourselves and places us outside ourselves, so that we do not depend on our own strength, conscience, experience, person, or works but depend on that which is outside ourselves, that is, on the promise and truth of God, which cannot deceive.
The pope does not know this; therefore he and his furies have the wicked notion that no one, not even those who are righteous and wise, can know whether he is worthy of love. But if they are righteous and wise, they surely know that they are loved by God; otherwise they are not righteous and wise.
