The Middle Ground, Right?

The angels' quote ability to sin or really more accurately their inability to do the right thing only comes into the picture when we consider that God also elevated the angels to a life of grace, much as he elevated us. And so the angels were elevated to an end that is beyond their nature and of which they did not have perfect understanding. Therefore it is possible for them to be ignorant of something and now we can see how sin can enter the picture.