And started out by killing Gilbert in a grotesque and taunting manner. If you remember, upon seeing Gilbert’s lifeless body Crowley realizes that till that moment he still had some faith left, part of him desperately wishing for God to keep safe that precious remaining comrade of his. The moment he laid his eyes upon Gilbert’s dead body though was the moment when his faith was gone for good, and with it, his hope for a peaceful life. Ferid erased it. Moreover, taking his masked taunting to the extreme, Ferid, having just crushed a good chunk of Crowley’s soul, even made Crowley apologize to him and beg him for help, all before the cross and Gilbert’s body. No seraph or even demon can be as much of a true monster as Ferid is.
Volume 2 of the Michaela novel goes on sale on May 2, I have it preordered (along with vol.11 of the manga), and I expect we will learn there that Ferid set up some ploy to eventually kill Jose, Crowley’s other supporting pillar, as well, which left Crowley absolutely broken and with a deathwish.