I'm not comfortable with how ~~とは...
is used in my textbook:
彼{かれ}がひどいことをした
とは
信{しん}じがたい。
That 信じる
is only transitive makes me think that ~~とは...
is a nominalization method. But, I've never seen that method of nominalization before. So, I interpret ~~とは...
to be a conjunction and imply a direct object as such:
He did a really bad thing, and I just cannot believe it.
The straight-up nominalization interpretation (which I reject because of the nominalization method looks strange to me) would be:
I find it hard to believe that he did such an awful thing.
So, what's going on with the ~~とは...
conjunction? / nominalization?
straight out of textbook
あの優しい彼がそんなひどいことをした
とは
信じがたい。
note
断った
とは
信じがたい
is used in the title because it is just shorter and should involve the same grammatical structure. If it's not, then learning the difference would be very instructive.