User blog comment:Pelinal Whitestrake/About Aka, Lorkhan and broken Windows/@comment-11345660-20140209010228/@comment-25047024-20140210233648

Well, the first flaw with your theory is that Akatosh didn't even exist at the time in which Alduin was worshipped by the Dragon Cult. Akatosh was created by Alessia who merged the nordic aspects of Alduin and the altmeri aspects of Auriel into a single god.

The fact that there are dragons and that their souls can be absorbed by another Dragon or Dragonborn already proves my theory... in a way.

And there is more than enough evidence. You just have to look for it.