If you go on line you will see all kinds of Protestants stating the the Catholic Church is not the true Church. Which Church do Protestants align themselves with? One Protestant web site says that1 Tim. 3:15 (the Church is the pillar of truth) means Christianity as a whole.That can’t be so because there needs to be consistency of truth, and mega denominations dont lend themselves to that. What is the Protestant “church?”
I think you could compare it to mixed martial arts, in the sense of universality. Here’s what I mean.
Mixed martial arts is an amalgam of fighting styles. There are a few rules and restrictions which prevent you from saying it’s an anything-goes no-rules free-for-all, but essentially, any form of fighting that qualifies as a recognized competitive fighting style is in bounds. In that sense, mixed martial arts is basically universal fighting. This is different from the marks of universality as defined by the CCC, but we are talking about something different here. We are talking about Protestants, and this is how they look at universality.
So this is the way it breaks down. You start with defining who should be recognized as a Christian. Generally, that boils down to being both trinitarian and monotheistic, so marginal Christians like JWs and Mormons and Christadelphians would not typically be recognized. “Marginal Christian” means we acknowledge your own assertion that you represent true restored Christianity while declaring us all apostates, but we don’t recognize you or agree with any of that. Neither of course would Muslims or Jews be included, despite being monotheistic. Trinitarianism is the other point, and you basically need to have both those things. Two points make a line.
Breaking it down a little bit further. Catholics are typically recognized as fellow Christians by informed Protestants, the more well informed the more likely they are to recognize them correctly. Less well informed Protestants may not recognize Catholics as really being Christians, typically because they don’t have a coherent way of delineating Christian from not. The two-point litmus test I just mentioned may be news to such a person, and basically, they exclude people-groups based on how much anger they feel toward them rather than any coherent reasoning. But for Protestants who are well-informed and fairly coherent, there is a fairly universal set of church families that are recognized very reliably- Catholics and Orthodox, both Eastern and Oriental, even if we know hardly anything about them or their history. Also Protestants, which is the people who hold to the five Solas and have a bit of variety between the mainline Protestants and the Evangelical Protestants of various types. Excluded with some regularity would be marginal Christianity- specifically, those who do not believe in the five Solas (and therefore lack the leading essential characteristic of Protestantism) but more importantly are also either non-Trinitarian or something other than monotheistic. The main point of difference on that last one is the question of whether a Mormon or JW can, individually, seek after the truth while staying affiliated with a problematic organization and be saved in spite of it. Opinions may vary and lead to some uncertainty on that point. In the larger sense, however, marginal Christianity is fairly well defined from an institutional standpoint and is categorized in this manner pretty reliably.
To answer your question, the Protestant concept of “the Church” consists of all Christians that are recognized as Christians- the chief marks being those of trinitarianism and monotheism. To us, this is the universal church, and our idea of universality is different from the Catholic idea of the same- ours is more akin to mixed martial arts, where there are many distinct fighting styles that are all encompassed by one sport. Are we aware of how much difference there is between these different groups of Christians? Yes, as a matter of fact, we are. And those differences are a key mark of something that’s truly universal and appropriately inclusive, just as mixed martial arts is defined as being fairly universal
because it allows for basically every kind of fighting within the broader discipline. If it didn’t, it wouldn’t be quite so universal now would it. Do we have a problem with all these differences? Not really, as long as everyone is fairly consistent with recognizing the same people as Christians and having consistent, coherent reasons for doing so.
We have one circle drawn around all sorts of groups recognized as Christians, and a bunch of smaller circles drawn around more specific faith-groups and traditions. It’s not our goal to eliminate all the smaller circles and present the world with a larger circle that’s been drawn over twice. That would be impractical and quite frankly not good for Christianity as a whole. Instead, we circle all of Christianity and try to make sure everyone is on the same page with where that circle should be. And that is the Protestant “church.”