Come on, now. I have explained this several times already...The day that Baptists, Calvinists, and Methodists agree clearly on doctrine (even important things like who can be baptised), then I'll go along with your idea that the Spirit of Truth gives everyone a systematic lesson on the Scriptures and their meanings without any distortion.
Regards
You know very well that there is no defined complete doctrine among all Protestants. It would be great if there was, but such is the nature comparative freedom. I see your argument as being "how can the Spirit lead me to one truth and a Methodist to a completely different truth? We both can't be right." I understand that, but as I have said before I know the Spirit does not work in the fashion of complete revelation of doctrine to believers on day one. It is an individual process of sanctification.
In addition, there can be misperception of the part of the receiver. Ultimately, if you say "why should I believe you over a Methodist?", I agree, maybe you cannot know. All I can do is put up my beliefs against what the Bible says, and let the other denominations speak for themselves. :)