They're far closer to Reapers than to gods.

[He crosses his arms loosely, a sure sign he's agitated, but not incredibly so just yet.]

The last thing that any of us need is a conflict with the shinigami. Lucifer has said he will not use souls again, but...

[Castiel knows how easy that is to say. Just that Lucifer's been doing so makes him remember how little effort it takes, and how much power it grants, and what that could be used for.]