"To begin with, I must deny that there are seven sacraments, and for the present maintain
that there are but three: baptism, penance, and the bread." - Luther
I'm not the biggest fan of Martin Luther, and I think better Protestant thinkers have evolved from the Protestant tradition. (As a Catholic) I like reading those thinkers and their (more fair) critiques of Catholicism more than most of Luther's stuff. Of course, this specific treatise likely has a political motivation, so that explains its "color" and lofty rhetoric.
But still, when I read Luther (or his debates), I am not very impressed. He's bombastic, loud, and rude, and many times he ventures way beyond his element (he engages in metaphysics to his detriment) or rambles in a way that makes reading difficult.
Yet Luther is important - no ESSENTIAL - for Catholics to read in order to understand how the Protestant Revolution changed everything, and why the the faithful were so enraged at the time. This is bound to better our witness to the world. (It is also bound to help elucidate the complex political dynamics that Protestantism became involved in).
Regarding this treatise specifically, the rambling nature of Luther's arguments showcase his chief difficulty: Luther was grappling ... alone ... to build a new tradition from the ground up, and at one point even asked his reader in the treatise to disregard ALL the writings of the Church Fathers about a certain subject for his (Luther's) singular interpretation. What a burden he takes on (one that he did not meet in my view!).
Here's part of the quote: "What shall we say then of the canon of the mass and the patristic authorities? First of all, I would answer: If there were nothing at all to be said against them, it would be safer to reject them all than admit that the mass is a work or a sacrifice . . . . [speaking about a view pertaining to the mass, which he seems to misunderstand that the mass only works if Christ first gives His body to us, which is not a work of man] - Luther in his section about "Bread"). This is a shamelessly lazy way to get rid of HUGE pieces of evidence/arguments against your position. I commend anyone to read that part of Luther's argument, it is not well done. He simply moves on without addressing this huge historical problem.
Lastly, I could not help thinking: would Luther even be recognized by most American Protestant evangelicals today?
In his sacrament of "Bread," he calls for the abandonment of transubstantiation for consubstantiation, where the both the accidents, substance of the bread AND the accidents, substance of Christ's body are present along with the bread (for Catholics, the accidents of the bread remain and substance changes to Christ). But notice, the substance of Christ is still there for Luther! Christ is present in the Lord's Supper, and it is not a mere symbol (as argued by Zwingli). Arguably, Luther tweaks transubstantiation (I, of course, contend he transmogrified it) in a manner that still maintains a level of fidelity to Catholic modes of thought.
In his Baptism comments, he seems to preserve its regenerative effect, even affirming infant baptism! And he expresses his ignorance on a partial birth baptism of an infant. Once again, he seems to preserve and tweak the modes of thought that come before him.
In his Penance section, he acknowledges the necessity for confession TO ANOTHER CHRISTIAN! And he even argues that each individual Christian has the power of absolution. Notice, he's implicitly admitting that ABSOLUTION is a legitimate thing. (N.B. he admits that the specific "Private Confession" employed in that time cannot be proved by Scripture alone, yet he still believes confession is from the Scriptures)! I rarely hear these types of argument spoken by my Protestant brothers and sisters. But Luther is right: The Bible clearly tells us to confess our sins to one another (James 5:16).
So, I wonder how many American Protestants would recognize Luther's views . . . and how many would lament at how "Catholic" his views sound. Ultimately, the non-recognizability of Luther hints at a problem emanating from the Revolution and its ever-revolving character - a problem that I save for the Church Historians to tease out.
For what it's worth, I think Luther was attempting something that he could not successfully execute and that is why he slowly abandons Catholic teaching to his later more explicitly non-Catholic views. Luther was trying to build a new church with nothing but his personal wisdom, motivation, and shrewdness in choosing which historical traditions to preserve. Notice, this is NOT a reformation (He's not trying to make bad Catholics into better Catholics), this is a complete change/revolution of the Church where one seeks to substantially (excuse the pun) destroy or abandon a past institution to create a better one - a reformation seeks fidelity to the former institution for its growth and healing.
A revolution abandons the former for the perceived better and its promises.