I'm not redefining the word. I'm using agnostic in the sense in which it means. First and foremost, I am only agnostic when it comes to God, or a supreme being. I do not think it is possible to know if God exists. I may believe that God exists, but belief and knowledge are separate. I accept the possibility that I may be wrong. Simply put, I do not think that we have the required knowledge needed in order to make a rational decision on whether or not God exists. Thus, it falls into the realm of faith, and for me, I must then stay open to the possibility that I am wrong.
This does not effect that manner in which I view Jesus though, so your statement before simply was not correct.
Also, one can know a person who is dead (or as I said, died. I never stated that Jesus was still dead. In fact, I was silent on the matter). I can know my grandfather, who I never met, by examining his life through other witnesses.
As for the orthodox matter, the idea of orthodoxy was created by the Catholic church. Once one begins to distance themselves from the Catholic Church (and one could even make the case that once when moves away from the historical Roman Catholic Church), one moves away from orthodoxy. The matter gets a little muddled as there is also the Orthodox church, which split from the Catholic church. Here, we get two sets of orthodoxy.
If we push this further, when the reformation began, other forms of Christianity formed, which also took on a idea that they were the orthodox. Each time, we have a new form of orthodoxy, and new sects being called heretics. And yes, the Evangelicals were called heretics as well.
The problem is that the term orthodox basically means right thinking. Since there is no more central authority for the church, there has become a plethora of right ways to think. And the term orthodox or orthodoxy really has become pointless unless talking about one of the Orthodox churches.