Some people say that nobody is always right - Christ excepted of course - so individuals ought to make up their own minds about what the holy scriptures really teach. But if nobody is always right why would self-reliance work? And if one relies on the Holy Spirit to guide one into all truth then how does one account for differences that arise between individuals who think this way?
A more serious reply than my previous one (now I'm on a proper keyboard rather than a touchscreen).
I think your opening premise is flawed, and so from there the rest falls apart rapidly. The idea that nobody is perfect and therefore we should make up our own minds represents both a balance and a warning. A balance in the sense that we should read and understand for ourselves rather than merely parroting last Sunday's sermon or the latest "must-read Christian book" or whatever. The warning in the sense that we too are imperfect so we should continue to "test all things, hold fast what is true", which is where meeting for Christian fellowship is important.
In regard to the latter I fear that to a large extent the churches of today are little more than talking shops. The format is much the same more or less anywhere - sit in seats in rows facing the front, listen to the notices, the leader says a few prayers, then someone delivers a sermon, all interspersed with singing a few songs, then go out back for coffee and talk about the events of the week. Anything relating to a more personal struggle, trying to thrash out just what a particular Bible passage means, is shunted to a smaller meeting. In fairness, not much would get done on a Sunday if it were little more than an open mic session where anyone could expound on their thoughts regarding any particular verse but the tendency for Sunday morning services to become rather impersonal is perhaps a warning that we should be aware of how easy it might be for people with needs to slip through the cracks and become somewhat anonymous within the congregation.
Relying on the Holy Spirit to guide us into truth may result in differences in a number of ways.
First of all, as psalms91 mentioned, it's very easy to filter the leading of the Holy Spirit through the lenses of what I want to do with my life. And what I naturally want for myself is a bit of security, a bit of comfort, maybe a bit of cash behind me to tide me over any unexpected bumps in the financial path, and so on. The chances are, left to my own devices, I'm not going to choose a path that's rocky, that provides no comfort and no security and in which I'm living more or less hand to mouth with donations coming in moments before they are needed. So on that basis if the Holy Spirit is leading me towards a lifestyle like that, just as I got used to driving my nice new car and wearing the fancy new watch I just bought, my nature is going to be to resist it. Much more comfortable, much better (in an earthly sense) to stick with the comfort and console myself that people like Joseph of Arimathea were wealthy, so maybe I just misheard what the Spirit wants for me.
Secondly, some people are still prone to put certain leaders on a pedestal and figure that the Holy Spirit speaks through them and therefore they are above reproach. Some of the so-called prophets within the New Apostolic Reformation are bad where this is concerned because they fiddle with Scripture, misapply Scripture, and then act as if the matter is settled and the word being presented is true. Some time back on The Elijah List a "prophetic word" was presented along with reasoning that was little more than the "prophet" said it was true, the web site owner said it was true, "by the mouths of two or three shall the matter be established" (Deu 19:15) and therefore this was a word that you could "take to the bank". Sadly the reasoning collapses as soon as two people agree that the "prophecy" was garbage, because using Scriptural reasoning in the style of The Elijah List it was possible to prove that the "prophecy" was simultaneously truth and trash.
Thirdly, it seems ever-more popular to insist on a single objective truth. In most cases this is appropriate but as soon as our personal walk with Christ is concerned it isn't necessarily so. "Thou shalt not commit adultery" is an eternal commandment that applies equally to all of us but "Go to Bangalore and preach to the street children there" might be a calling given to one of us but not another. If my calling is to minister to the street children of Bangalore then doing anything else is sinful but your calling may not be to go to Bangalore and therefore for you to stay firmly where you are may not be sinful. So a discussion over whether or not it's a sin to not go to Bangalore is meaningless because the answer is yes for some and no for others (here "go into the world and preach the gospel" is fairly open-ended, as "the world" could mean Bangalore, Bangkok or Boston). The same would apply to anyone who had a specific calling to a particular form of ministry - if God is calling me to be a minister in my home town but I decide that I need to "go into the world" so fly off to some exotic location to preach I'm failing to answer God's call just as much as the person who was called to Bangalore but decided to stay in the air conditioned comfort of his regular church.
