Jesus clearly saw himself as a reformer since he spoke of "the new covenant" in relation to "the old covenant". He saw himself as the messenger bringing the Judaist religion to all peoples. Christianity remained a mainly Jewish phenomenon until it was forced out of the Jewish pantheon of sects and became its own religion. Actually as a part of its own success.
Contrary to Jesus' failure of keeping his message within the Jewish domain (and rather expand the Jewish domain to cover all peoples) Zarathushra sems to have been far more successful at keeping HIS message within the context where he taught and practiced his beliefs. Folk Zoroastrianism co-existed with Zarathushta's rather elitist message within Zoroastrianism for over 2,000 years. Parviz and I belong to those who regard this ENTIRE spectrum as The Zoroastrian Religion, as a culture or practice rather than as a theology to be followed. We are now free to do what we want with this heritage and it is our responsibility to act wisely with this enormously rich heritage. I believe we can do so while keeping our own beliefs uncompromisingly.
Regarding Ahura and Mazda in The Gathas: Zarathushtra rarely uses the two terms together, he speaks either of Ahura or Mazda, not because they are two entities but because the names obviously illustrate different aspects of The Divine to him, that which is vs that which is but also has mind. Which also answers Dino's question regarding Zoroastrianism and Pantheism (or Panentheism): Zoroastrianism must be regarded as Pantheism-Plus (or Panenetheism-Plus, as I believe you and Dina would prefer).
I do agree that Asura/Asura was part of the pre- Zarathuhtra millieu.
However, I would not go as far as saying that Ziism is a continuation
of ahurayasna. To start out with Ahura/Asuras were only one of the
types of gods the pagan aryans believed in
As a matter of fact if Jafarey is correct, and I have learned the hard
way that he usually is correct in linguistic matters concerning the
Gathas, Z himself says that he is calling God by a new name. Z's
doctrine is so radically different from anything in his time that I
cannot agree that he is but a reformer. Sure he used his culture and
the terminology all were familiar with but he totally changed
everything and, indeed, even the very meanings of some words he has
apparently changed as well.
I mean calling Z a reformer of aryan religion is like calling Jesus a
reformer of Judaism (which he might have been at least there is far
more evidence for that that for Z as a reformer of aryan religion)Or
that Mohammed was a reformer of Arab paganism, Xianity and Judaism.
The only way that we can make such a case, IMO, is if we redefine what
a reformer is.