Does anyone recognize this phrase?

“My sins are legion and I am become a monster in the eyes of God.” It was referenced several times in a book I read called The Uncanny. This may not be an exact quote, but it’s close. I believe it must be from an Opera, and I believe the author to be German. I’ve googled it and come up with some strange links, none of which have anything to do with opera. I get really wound up over stuff like this. It took me two years to find out the title for Yellow Ledbetter but it was worth the wait. I hope I don’t have to wait that long for this.