A Catholic need not “build” his faith in that manner because all of the answers are answered before he asks the question. It is only human folly (or perhaps vanity) that makes any of us think we have “discovered” something new.
I do not intend to be insulting (I certainly hope you have that impression of me by now), but I think you identify a real misunderstanding between the two camps and come at it precisely backwards.
It’s really pretty straightforward. If the RCC is not the “true” Church, then by definition many of their pronouncements are wrong, cannot be infallible, and any Christian who blindly follows them is in some measure of danger. Since no other “organized” denomination could be the single true church, it must be a nebulous body of believers tied by the Scriptures and by the HS. Thus, your confusion makes perfect sense.
If the RCC is the Church that Christ founded as His Body and the working of the HS is through that church then you present a logical impossibility. An individual cannot be lead by the HS to conclude a spiritual truth in conflict with Church teaching because the source of the two is the same and does not change. When the Pope speaks infallibly it is only because it is God speaking through him, just as God has done for at least four thousand years. It is not because he is somehow imbued with some extraordinary power to create new “truth” any more than we might decry a NC who believes that the HS has “led” him to a “new” truth.
You see, the confusion is not whether or not a Catholic can be individually led by the HS... of course we can. It is whether the HS would ever lead us anywhere other than where He has led the Church for two thousand years. You postulate a scenario where the HS leads a Catholic to a foundational “truth” apart from what “someone down the line” has taught. I claim that scenario is a “null set”.
Does the HS lead individuals to truths that are new to them that they do not even know the Church has taught? Certainly, and the experience is just what you describe for yourself, I recognize it. Does He lead us on topics that the Church adresses that are not issues of salvific faith (like how to handle a pedopriest)? Yep. Does the HS teach us individually on topics that the RCC has never even mentioned? Of course. But does He lead us about in dozens of contradictory directions to “new” “truths”? No. The journey is taken anew by millions of Christians each year, and may seem “new” to each of them (and is no less profound for being taken before), but the destination is (and must be) the same since there is nothing new under the Son. “Jesus Christ. The same yesterday, today, and forever”
This is not to say that those who disagree with the RCC are nor Christians, not saved, or not honestly seeking His will. It merely means that “fell short of the fullness” as you have no doubt heard it said.
Here's a question that came to me while I was shoveling show from my driveway. First off, let me admit that it falls somewhere (at least in my mind) in the realm of mental gymnastics. But I found it an interesting question nonetheless.
Which would be better for me to be: A Catholic who had grave personal doubts about the Immaculate Conception or a Protestant who believed strongly in the divinity of Christ? This is just for fun. There will be no grades given for your answers.
The problem that I keep running into with the statement "A Catholic believes..." is that your (Catholics in general) belief rests upon the idea that there is a monolithic true Church that is infallible. But if the people in the pew ain't having it, it doesn't really matter that the Church is infallible does it (at least to said people)? It's like me saying that socialism works in theory. Which of course it does. It's actual track record is somewhat less than stellar (please do not take that as me trying to associate Catholicism with socialism, they've done a good enough job of that themselves in Central America. Ok, that was me associating Catholicism with Socialism but it was too easy to pass up.... My apologies).
So again, when your system rests upon the absolute authority of the church (and you would point out guided by the Holy Spirit), it's only a nice little theory when the people in the pew are wrapped up in animism as much as the sacraments. Yes? No? This probably comes off as a bit too clever or none-too-clever but maybe if I keep repeating my idea in different ways some dim idea of what is running round my mind might make its way to yours....
Abraham was the first pope?