I always tended to believe it, given that you have a god helping you out. But I do like me some ambiguity.
You mean Azura? Not exactly a god, and (s)he clearly had her own agenda, namely taking down the Tribunal for stealing away her people's worship and humiliating her. She created the prophecy in the first place, you're just the first "chosen one" of many that doesn't fail.
In the game you're being played as a fiddle by the Emperor, a Daedric Lord, Vivec and even Dagoth Ur to a point. It would be rage-worthy, if you didn't become so awesome that Bethesda had to send you off to Akavir in Oblivion.