Well, in that case, you may want to strike As I Lay Dying from my list of recommendations – they’re Christian metalcore, haha. (But still pretty dark, imo)
From what you describe though, I definitely stand by all the other links I posted, particularly the Tristania one (death metal growls, choir singing latin, melancholy baritone singer, siren soprano singer, all intermixed with lyrics about the death of God and Jesus being a lie).