My response to you gets its own post
What you're saying about the pope filling the role as the guide and guardian of truth is what I was referring to in the OP. The way you articulated it though is new and provides extra detail so thanks! That sorta lets me see the way this could be applied in protestantism...
What I'm thinking about specifically (and this isn't a fully fleshed out or developed thought) is the idea of sola scriptura. Now, I'm going to deal with the Lutheran view here, which is quite different from your normal protestant. But here's my train of thought:
We know that the Spirit is the guide and guardian of the truth (John 16:13, 2 Timothy 1:14). Therefore, we can also say that it is the Spirit who protects the Church from errors (Matthew 16:18, 1 Timothy 3:15). Luther (rightfully) saw errors in Rome during the 16th century. The pope was removed as the "undisputed guide, guardian and "Spirit of Truth"" as you put it, and so something was needed to fill in. Without a guide, how can we know what to believe? (NB: I realized after writing this that this is almost word for word what the Eunuch says in Acts 8:31 lol)
The answer to that was Scripture. How we understand the Logos is ultimately determined by, well, the Logos. We reject the council of florence which officially defines the Roman eternal procession of the Holy Spirit, so in theory we could still hold Orthodox beliefs on this, but because of the wording of the creed, I tend to think that we naturally assume that the Spirit proceeds in the same way from the Father as from the Son. So we in practice hold the Roman view, even if in theory we are ambiguous.
In any case, we have elevated the Logos above the Spirit because rather than trusting all the places where the Spirit has promised to work (through the Church, the Sacraments, and the Word), we only trust two of them (the Word and Sacraments). We elevate the Logos over the Spirit and thus supordinate the Spirit's role in preserving Christendom.
In other words, even if we don't dogmatize what "and the Son" means in the Nicene Creed, our other doctrines still lead to the error. The pope replaced the Holy Spirit (and the Church). We replaced the pope with Scripture. I'd still argue that we're better off than Rome in this case -- at least our final arbiter for doctrine is one of the ways the Spirit has promised to work and come to us, unlike the false idea of ex cathedra statements, infallibility of the pope, etc.
Does that sound correct or reasonable?
Of course, this still presents the problem of going against all the Church Father statements that seem to pretty clearly argue for Scripture alone (in the Lutheran understanding not the dreadful generic protestant view)... so again I'm at a slight impasse. (But twenty minutes ago when I first had these thoughts I realized for the first time, and actually articulated to myself that I just might be Orthodox and not Lutheran, which is a step beyond where I've been before (and am at this very instant lol) as a mere inquirer and someone with a like for orthodoxy)
Sorry for the long post