Howdy, yeah I saw your post in the other thread.
I think I might have a problem with your use of the term "justified" because certainly from Jehovah's Witnesses' viewpoint they do feel that the types of beliefs and practices you identified are "justified by the Bible."
But your question of whether they are "justified by the Bible" actually calls for discussion and essentially exegesis and interpretation of the Bible and that is of course a very sticky wicket.
I think your subtextual point is very valid and is what I find interesting because it is somewhat in tune with my own philosophy and approach to the Bible. What I would say in short is that I think when anyone relies upon the precise wording of a scripture, right down to the minutiae, or even relies upon large passages alone to "justify" or to inform their own belief or to arrive at some conclusions, then they definitely run into a danger of the fact that the Bible itself as a text is not the "Word of God" in the sense that every iota is what God wished or would say to mankind. The Bible, if one is a believer, is only as a whole to be taken as God's Word. It is a flawed and broken record of the greater revelation to mankind which informs about God, his purposes, our purpose and ultimately His salvation for us. When Paul spoke of "All Scripture" being "inspired" he did not mean that "EACH scripture" was inspired or somehow divinely dictated to a human secretary - for he himself knew that in his own epistles (some of which were already being taken as "authoritative" in his own time) that this was not the case. No what he meant is what he said, that "All" as a whole, that is collectively, are useful to mankind and beneficial to mankind.
I think in that all persons, whether believers or not, could agree that the Bible contains very useful principles and guidelines for living. Beyond that, for the faithful, it further contains a roadmap to salvation and also information that reveals the nature of God to us.
-Eduardo