Many of the earlier pre-1930 Roman Catholic controversialists put forth the conclusion that the Reformation was a failure: it didn't produce any real fruit, and Luther's own words and the state of Protestantism at the time prove it. Protestantism isn't a movement of the church. It is the result of heresy, and heresy never leads anyone to true holiness. Statements are typically brought forth from late in Luther's career, indicting him of regret for starting the Reformation. I've looked at many such quotes over the years:
Luther: the world grows every day the worse for this teaching; and the misery of it is, that men are nowadays more covetous, more hard-hearted, more corrupt, more licentious, and more wicked, than of old under the Papacy
Luther: Our evangels are now sevenfold more wicked than they were before
Luther: People are Worse Than They Were Under The Papacy
Luther: The Gospel Made Things Worse Than Before
Luther: We Have To Pay for the Disasters of My Preaching
Luther: Protestants Have Contempt of the Gospel
Luther: We Do Not Act Upon the Evangel
Luther: I Have Given Up on Germany
Luther: Protestants' "Manner of Life" No Better Than That of the "Papists"
Luther: Under the Evangel, no one will give a penny... Under The Papacy it snowed alms
Luther: Those who ought to be good Christians because they have heard the gospel, are harder and more merciless than before
Luther: I fear that we are a greater offense to God than the papists
Luther: They accuse us of being rebels, of having destroyed the unity of the Church
Luther: We Germans are now the...shame of all the countries
Luther: All is forgotten that God has done for the world through me
Luther: Our (people) are now seven times worse than they ever were before. We steal, lie, cheat, . . . and commit all manner of vices.
Luther: There are nowadays almost as many sects and creeds as there are heads
Luther: I am now more negligent than I was under the Pope
It's one thing to argue Luther suffered from depression or had a despondency over the state of things, it's quite another to use his words to prove he had a sense of "failure and guilt" over the preaching of the Gospel, or that he was in agony over the Gospel going forth into the world and the trouble he admitted and expected it would cause. Luther wasn't postmillennial. While he was discouraged that the world seemed to be getting worse, his eschatological expectation can be traced back even to the early days of his Reformation work. For Luther, it was the end of the world. Things were indeed going to get worse. The Gospel was going to be fought against by the Devil with all his might. The true church was a tiny flock in a battle against the world, the flesh, and the Devil. He hoped the people would improve with the preaching of the Gospel, he often admitted he knew things were going to get worse because of the Gospel.
Here's the big picture, so to speak, in many Romanist minds: the Reformation was a failure and was morally bankrupt. It didn't produce good fruit, nor were its result any better than those of the corrupt church Luther and the Reformers fought against. Luther knew this, and admitted it. He died despondent over the mess he created. Heretics never lead good lives, nor produce good fruit. Since Rome is the true church and the Reformation was a failure, we as separated brethren must reunite with her. Trent cleaned up the situation as well, so what are Protestants waiting for? It's only by being in the true church that someone can attain true holiness. Simply read through Janssen, Denifle or O'Conor. This sentiment jumps off many of the pages.
The most recent edition of Luther's Works (volume 58) focuses specially on Luther's later sermons. The introduction makes the following pertinent observation:
The tensions between Luther and the Wittenberg congregation came to a head in Luther's resolution during the summer of 1545 to abandon Wittenberg and to retire with Katy and his family to the countryside, until he was finally persuaded by the petitions of the elector and the university to return. But though dramatic, Luther's brief self-imposed exile from Wittenberg during the last year of his life was in fact not unprecedented. In 1530, before his departure for the Coburg during the Diet of Augsburg, Luther had announced that he would not preach in Wittenberg anymore, and similar threats, sometimes carried through for several weeks at a time, were repeated both before and after.
Luther's complaints about the Wittenberg congregation have been taken as evidence of his personal despair at the end of his life and as an admission of the broader failure of the Reformation at the hands of its foremost exponent. But Luther's sharp criticism must be understood in the context of his own theology and apocalyptic understanding, and set alongside his contemporary statements (often, indeed, within the same sermons) of satisfaction and hope. Although Luther discouraged and even ridiculed efforts (including those of his own friends) to predict the end of the world, he understood the history of the Church, from the time of the apostles to his own era, in view of the coming Last Day. Throughout history, the true Church, gathered around the preaching of the pure Gospel, had been and would always be opposed not only by enemies without but also by false preachers and heretics in its own midst. Indeed, the ferocity of such opposition and resistance, spurred on by the devil, was one of the marks of the true Church and of the pure doctrine. In light of such an understanding, a Reformation that was an unchallenged success would ipso facto have been a failure.
As such, the faults of Evangelical congregations denounced in Luther's preaching were themselves testimonies to the purity of the Gospel being proclaimed in their midst; emphasizing them in preaching constituted a response to the theological claims both of the Antinomians, who denied that the Law should be preached to Christians, and of the Anabaptists, who were understood to demand the radical perfection of Christians in their communities. To be sure, Luther was in full earnest in denouncing sins of greed and usury and demanding their reformation. But the root cause, the fault of coldness toward the Gospel, became in Luther's preaching a confirmation of the truth of his doctrine. In his next-to-last sermon of February 7, 1546, Luther complained of the devotion of the Christians in Eisleben:
"If you do go to the Sacrament, you go and come away again like a block of wood, or you let other people go to it and stay away yourself. So, too, you hear God's Word and that God's Son has died for you with no more devotion than if someone had said to you that the Turk had slain the sultan or the emperor had captured the king of France or some other tale, and you think it has no bearing on you, and you are as cold as ice and do not enkindle your heart nor take any thought for your soul or eternal life. That is what careless, wild people do, who take no thought for God."
But Luther is not in fact concerned here to distinguish better Christians from worse ones, denouncing the coldly indifferent and demanding warmer devotion. Instead, he insists that this resistance to the Gospel is the result of original sin even among the best of believers:
"Yea, indeed, and we, the best of Christians, do the same. We are able neither to possess this joy nor to bring it into our hearts, though we gladly would. It will not penetrate the heart, bone, and marrow; it does not savor and live; it does not comfort and gladden us as it should. The old Adam and our sinful nature do this; the sin, which still lurks within us, compels me and you so that we do not believe it."
Luther's answer, then, is not to demand perfection, but to direct his hearers back to the catechism:
"Therefore St. Peter says in the Second Epistle, chapter 3 [:18):... "Grow in the grace and knowledge of our Lord and Savior Jesus Christ." Prepare yourselves, you Christians, so that you do not think: "We have learned and believe all there is to know about the catechism, Christ, the Sacrament, Baptism, and Absolution." You have just begun and are still very young students. Therefore, think about how you may increase and grow and always continue learning what it means that Christ died for your sakes, so that this does not remain on your tongue like foam or spittle but penetrates and enters the heart, so that it comforts and gladdens you."
After all, Luther says, it is only the heretics, like the ancient Donatists or the modern Anabaptists, who imagine that individual Christians or the Christian Church as a whole can become entirely pure and perfect in this life. The lackluster faith and devotion of Evangelical Christians described by Luther thus becomes, in the context of his theology, a proof of the truth of Lutheran teaching over against Anabaptist claims. Luther's "disappointment" was as much a homiletical posture determined by the expectations of his theology as it was a matter of dispassionate observation.
Luther's complaints about coldness toward the Gospel appear alongside and indeed presuppose his confident declarations that, in fact, the Gospel is being abundantly preached and proclaimed, not only in the churches by faithful pastors, not only in the schools—of which Luther boasts even as he pleads for more generous support—but also in homes, among parents and children, as he says in his last sermon: "You hear at home in your house, father and mother and children sing and speak of it, the preacher speaks of it in the parish church." The Gospel is thus communicated from one generation to the next—and back again. It is to the children, with whom Luther habitually associates knowledge of the Christian Creed, that he refers adults who have questions about Christian faith, and upon the youth, "the seedlings with which the Church of God, like a beautiful garden, is cultivated and propagated," that the reformer continues to place undiminished hopes. The Reformation, as Luther understands it at the end of his life, is neither an accomplished event nor a step along the progressive way to the full purification of the Church, but it is a continual struggle, carried out through the preaching of the Law and the Gospel, to be renewed from generation to generation until the Last Day. [LW 58:xx-xxii]