These issues are very complicated, and in my view seem to deal more with epistemological concerns than issues of dogmatic authority, at least as far as the OP's question is concerned.
That being said, if one submits one's judgment and interpretation of Scripture to the church's creeds and confessions, then one will still be functioning as the decisive factor, because then you'll need to apply reason and understanding to the historical data to figure out which church is the true church.
I hope that doesn't come across as pedantic, because I've thought these issues over quite a bit for myself. I just find it odd when some on here (not even necessarily on this thread, but I've seen this view on the PB) tout creeds and confessions in an overly confident way, the authority of the church, and that we should walk in old light. All of which I largely agree with, but if we took that tag-line consistently and not selectively, we should be in Rome or Constantinople.
I think that you must give the voice of the church a favorable weight and the benefit of the doubt, so to speak, in interpreting Scripture, but if you abandon your private convictions based on Scriptural study, you will end in your private convictions in evaluating history.
I don't see how that's avoidable. Because once you desire to submit to the church
in that sense, as a Western Christian, then you'll need to figure out who was wrong when it came to leavened bread, the Filioque, and papal jurisdictional authority over the other metropolitans/archbishops. To make it even more confusing, most Protestants would say that the West was right in the pivotal issue of the Filioque, and that the East was right when it came to papal power. So one will need to make a crucial decision as to what constitutes the church. If one decides on the West, then yet another decision has to be made as to who to submit to, namely, now between Protestantism and the Bishop of Rome.
And if one finds oneself interpreting Scripture and applying it to these controversies, i.e., the Filioque, justification, etc., in order to decide which church to submit to, then we're really back at square one, aren't we?
I'm sure that some might see that as sophistic, and it might be, but this is my sincere look at the issues. Ultimately, I would say, probably with the Confession, but I'm not going to cut and paste, that some places in Scripture are plain and easily understood by all, and that, regardless of which church is "right", there is a body of consensus there. If I am trusting Christ and Christ alone for my salvation, and find myself in agreement with the broad plains of Scripture, and squarely in the consensus of the church, then I think that's a good indication of standing and certainty.
When it comes to baptism and other issues, I would just recognize that
as important as they are, your salvation doesn't hinge on the matter. Live with a good conscience and interpret Scripture
coram Deo, and leave your failings and errors to His mercy.
