This? Is an argument that Castiel has become very familiar with thanks to Milliways.

And it is a subject that he does not have the time, nor the inclination to patiently debate right now.

Dean will simply have to learn to accept the quick way.

"You should show more faith."

Especially in the face of all he has seen.

Castiel allows the physical form that houses him to shift slightly. Only a small bit, but enough that the exposure of his true form sends the electric current in the building shuddering and flickering again.

And enough to cast the shadows of his wings on the wall behind him for a brief moment.