Question of doctrine

Here is a quote from Tertullian:

“Where diversity of doctrine is found, there, then, must the corruption both of the Scriptures and the expositions thereof be regarded as existing….”  Tertillian (160-225AD)

This brings some thoughts to mind.  There are one of two things going on.  Either one doctrine is correct and therefore all others are wrong, or doctrine per se doesn't matter and all the doctrinal debates and arguments are not worth the effort.  How then does one decide upon the truth or error of a doctrinal position?  Too often it comes down to who is the better debater.  But this is wrong.
Would God really leave this all of this so ambiguous?  Would God really leave us without direction?  The book of John (I believe) tells us that the Holy Spirit has been given to us for guidance.  And the only way that works is if the Holy Spirit is directing the Church, as a whole, not as a bunch of individuals.
(Hint, hint: The historic Orthodox Church)