Just wanted to share with you that Luther's primary goal was to expose Catholicism's false teachings. He was the former of Protestantism, which is the way for true teachings of Scripture. Catholicism has numerous anti-Christian teachings that needed to be brought out. There are so many false teachings in this religion that renders it non-Christian.
Teachings like "Immaculate Conception," which (if you look in the dictionary) teaches Mary was sinless, which is probably their most decadent doctrine. It has always been masquerading as a Christian religion and has many teachings that are not Christian; many do not read and study the Scriptures thereby not seeing the truth of this denomination.
I would only differ slightly. Luther's original purpose was not anti-Catholic. But it ended up being there specifically because Catholics vehementy opposed what for Luther was explicit biblical doctrine.
Luther felt he found the key to avoiding Christian Nominalism, aka a "dead faith." To know Christ personally by faith was central to the Christian faith, and took place simply by submission to the fact Christ can do what we ourselves cannot do. We accept his Justification by his Atonement, and not by anything we can do without him.
Catholics doubled down on their opposition to Luther's complaints, in particular his concern about "Indulgences." Even worse, they were duplicitous and tried to maneuver Luther into coming into a trap where he would be burned at the stake.
Luther realized how corrupt Catholic leadership had become in his time, and perhaps wrote off all Catholics for all time at that point? He identified them as "the Antichrist."
Those who departed from this Nominal Faith, replete with "substitutes for Christ," could find regeneration in his doctrine of "Faith Only." In other words, Salvation by "Christ Only," and not by the Works and Traditions of Catholic exclusivity.
My own view of Catholicism is that it is not "the Antichrist," though some elements of it are, to me, Antichristian. As you suggest, Mary's Immaculate Conception is non-Christian and can lead some to a virtual antiChristian proposition that any non-Catholic view is corrupt and lost. That is "Antichristian."
There are a number of wrongs in the Catholic Church, the absolute authority of the Pope when he speaks "from his throne," the exclusivity of the Catholic Church, the perpetual virginity of Mary, Mary being the "Queen of Heaven," prayers to the saints, and the veneration of religious tradition as a substitute for genuine Faith, etc.
However, many churches have problems with their congregations and with their own exclusive traditions. Where do we draw the line? A "High Church" is a State Church and naturally includes believers and unbelievers in its Congregation!
I would say that Protestants did the right thing in drawing a line between them and the Catholic Church. One must reform traditions that create non-biblical guidelines to living in Faith.
I won't call all Catholics non-Christian. But I would warn them of the sectarian spirit within Catholicism, because clearly, Paul condemned that!
