[Castiel's jaw tightens, because he can't actually answer. He doesn't know, because he can't remember, because of what has been done to all of them for the purpose of preventing one of them from becoming the next Lucifer.

He isn't about to explain any of that, so there's little he can say and he considers just hanging up. But finally, he speaks.]

Doubting God, or our orders, or our mission risks incurring the same fate that befell our world's Lucifer. Those doubts and questions were therefore kept silent, though they were considered by many for a very long time.