User blog comment:Derax-Pagani/Chapter 509: Kagura vs. Larcade Review/@comment-3285005-20161108025138/@comment-99.13.69.171-20161111214544

That situation would only apply depend on if the TC stealing their souls are not alone, besides that, that would depend on the level or each demon, like Galan, he would not be capable of devouring a soul with greater magic than his own. I don't know what holy magic has to do with this, but his magic was clearly superior to Merascylla which she explicitly stated, there was no way Escanor could use magic in that state. And holy magic does not guarantee a sure victory over a demon, it would depend on the level of magic they have.

You do realize that sting and rogue were in a tournament so killing was not an option in this manner. Or there was no way to assume that Juvia's water body would work ever time, it'a like a Logia user relying on his Devil Fruit powers but then get's surprised by a Haki user.