User blog comment:Woverine294/How did Thor lose his power to mjolnir and Female Thor claimed it/@comment-16461120-20150605000658

We actually don't know what The Unseen told Odinson. He whispered something that he learned from Uatu during Original Sin.

When Thor Odinson initially committed the sin that Nick Fury reminded him of, he became unworthy at that time. It was one of the numerous other times that he was not able to wield Mjölnir. He then somehow redeemed himself and was either not aware of the cause of his unworthiness or had forgotten it until The Unseen made sure he remembered.

When did this sin happen? We don't know yet, but if I had to guess I suspect that it was decades ago, since it's well known that Jason Aaron (the current writer of Thor) has been consulting Walt Simonson (a previous writer of Thor during the '80s) for more than two years regarding the progression of this ongoing storyline.

So why did something from his past make him unworthy again now? We don't know yet, but it could simply be that in remembering what he'd done before he tried to justify his actions once more in his mind, or worse, longed to do it again. ::gasp::

Mjölnir doesn't decide who is or isn't worthy per se, it simply recognizes who is or isn't.

In other words, it was Thor Odinson himself who realized he was unworthy after Nick Fury reminded him of something he'd forgotten he'd done. And just like every other time this has happened, it seems pretty clear that it's in his own head, so only he has the power to sort himself out and be worthy again.

Y'all don't need to worry so much, true fans of Thor will follow the story and find out the answers to these mysteries, and when the arc ends, Thor Odinson will once again heft Mjölnir to the heavens as the God of Thunder. Until then, he should probably focus on overcoming his erectile dysfunction. (Poor Sif.)