"There are no Protestant Churches in the proper understanding of the word Church because they can only have sects."
Says who?
Says the partisan sectarians of the Latin Church, and perhaps some others who hold to the notion there must be some (imagined to be) unbroken chain of man-occupied office of Church administration in order for an ecclesiastical organization to at all also be a Church. The Lord Himself set no such artificial limitations.
When Ratizinger wrote about (his own views) of what Church was, and what qualified, he didn't stoop to calling all those ecclesiastical organizations outside of Roman Catholicism "sects" as your have done here. Yet his own definitions undo & unravel themselves once one looks towards the root word for "Church".
Additionally, proof-texts which Romanists read-in-between-the-lines of, where they claim that Christ did set such limitations; that Christ's own ekklesia would never be in error ----and that that one ekklesia is (of course!) their own and absolutely none others ---is about as sectarian as it gets.
The ones who originally invented that limitation were as [then] latter-day Sanhedrin, inventing doctrines that perhaps had some initial sourcing from within Scripture, but came to the fore in the shapes which they did more from within their own developing traditions, which arose not narrowly shaped from the Word and original Church traditions, but also strongly influenced by their own mere & lesser customs concerning those considerations.
Similar to what rabbinical teachers propound, portions of what they would insist upon were God's own instructions simply were not the Word of God as they (the Sanhedrin, and the latter-day Sanhedrin) were wont to advertise those doctrinal inventions to be.
It would be good to remember right about here that Paul, as he noted, was taught by no man --- meaning that he was not taught by other Apostles concerning Jesus, yet was used by God as instrument within the Church in establishing and furthering the Church.
From outside of the initial circle of chosen Apostles was added by God (not coming up through the ranks of church teaching, through submission to the teachings of the Apostles) the very one who (arguably enough) most defined what the Church was in it's various assemblages of that which came to be known as (plural) Churches of the one universal Church.
Many members -- but one body, and not one which necessarily had as it's headquarters one particular ekklesia from among them all to rule over all the rest.
Using later arising man-made shifts of definition for what the Church is in order to allege that; ecclesiastical organizations arising from the Reformation are not Churches, is nifty self-serving circular reasoning, but circular still.
There must be definition of what Church is coming from outside that very thing, a word not being able to define itself, lest that Word be God Himself. Hence the need for such precepts as sola scriptura to keep promoters of that inevitable alternative, sola ecclesia, in check.
Despite your own and many other 'Catholics' steadfast denials, the Word of God as supreme (reliance upon the Holy Writ foremost to guide) being over and above whatever exercise of ecclesiastical authority there may be ---WAS among early Church precepts & understanding, Christ Himself providing examples of the principle in his own actions, and words.
I think it best that we all take Him at his own word, rather than rely upon partisans -- like [Roman] Catholics who think their own ekklesia the only one, along with all the blather about others "not having the fullness of faith" etc., when that alleged fullness includes "extra" inventions far outside of (and at times in conflict with) the more original Church purposes and charter.
“Says who?”
Common sense. If someone has chosen to be a member of a sect that means he either is ignorant of the FULL truth or is deliberately rejecting some of it. There is no other possible logical understanding.
Even Protestant theologians intuitively recognize this fact and over the last 500 years have honed the idea of the “invisible church” to try to get around it.
As Jason Stellman, once a stalwart Protestant, put it:
“In a word, I fought the Church, and the Church won. And what it did was beat me, but it didn’t draw me, entice me, or lure me by playing upon some deep, latent psychosis or desire on my part for something Protestantism just couldn’t provide. Catholicism went from being so obviously ridiculous that it wasn’t even worth bothering to oppose, to being something whose claims were so audacious that I couldn’t help opposing them. But what it never was, was attractive, and in many ways it still isn’t.
“But what Catholicism is, I have come to discover, is true.”
The rest of your post seems to be the usual self-reassuring blather I’ve come to expect from you rather than an actual argument of any substance.
Christ sent a Church. He never sent a Protestant sect. All Protestant sects are just man-made bodies with no authority. It’s just that simple.