I'm currently reading through MacCulloch's Reformation and I am about ~160 pages in, but I had a question. It seems like Luther was mostly just against the Pope and indulgences (at first), but then got excommunicated and called a heretic so he thought, "Screw it" and went all out.

So, why not just advocate for a reunion of Orthodox/Catholicism? Or convert to Orthodoxy?

(I know the evangelical theological positions of the Reformation don't match Orthodox theology, but it seems like that theology grew and progressed over time)