Frank -- my take on it is that in Isaiah 9:6 it is talking about future events , the messiah will be called Mighty God yadda yadda , not that he was at that time worthy of the title. I believe that Jesus was promoted after his resurection , like it says , he became less than an angel to be exalted over all things. Mathew 28:18 is a good cross reference where jesus himself says he is given all authority in heaven and earth . So apparently somebody gave him that possition not that he always had it .
Heathen:
I honestly think you should take another look at the verses. The true test of scripture is not making it fit to some future context, but looking at it as the author wrote it and how his ancient audience would have viewed it. The bottom line there is they referred to Jehovah the subject God as "Mighty". There is also Psalm 24:8 " Jehovah strong and mighty" . Again Jehovah is called "Mighty" (use is same Hebrew word gibbor). Then Luke 1:49 Mary says, "for the Mighty One has done great things for me—holy is his name." Then Jeremiah 32:18 " the [true] God, the great One, the mighty One, Jehovah of armies being his name".
I really don't think it is a big deal. So much arguing and debating over something that is obscure (not clearly explained) in the bible. In other words it has to be exegetically explained like you did above. "Well what was meant there was....." etc.
However when scriptures are plain and clearly stated they are ignored. Such as Jesus saying, "If someone in authority "impresses" you into service 1 mile go with him 2" yet the dubs reject compulsory service, even though they recognized the authority as divinely instituted. Or Matt 18:15-17, which clearly says sins should be handled "between you and him alone" and later Jesus said "77 times you should forgive" etc.
I am being the devils advocate on this subject, it is the dogmatism of both sides that does not escape exposure, yet people can be so defensive and intolerant. It is a given that if you were raised a dub you will be prone to keeping the particular Unitarian view of that tradition. (there are many Unitarian viewpoints as you no doubt know). Likewise the one reared in a Trinitarian tradition is going to lean to that view.
Can't we just live and let live and honestly recognize that it is not important?
Frank75
PS How do you explain John 2:19 "Break down this temple, and in three days I will raise it up." Was Jesus telling the truth there? Was it he who raised himself from the dead? Would not saying "tear down this temple and God will raise this up" been more accurate and less offensive/stumbling to his audience?