Ehhh, to me it's always been primarily about the sound, because the lyrical content you described could practically be applied to most music within the general umbrella of "metal." Even Black Sabbath could have been considered 'death metal' if all it takes is a religious/supernatural theme. Most thrash bands of the 80s also covered the same topics. FWIW, I don't care much about the lyrics. The overall feeling I get from the music is more important. In fact, with some of these bands, I'd rather not know the lyrics, haha. I'm not here to be an elitist though; people can like what they want, and can call their favorite music whatever they want. But if I'm in the mood for death metal, then there is a pretty strict set of criteria I apply -- some bands have it, others don't. Usually the 'modern' bands tend to incorporate too many elements that are not in line with the death metal aesthetic (i.e. -- pristine production, guitar tone that is too polished, and drums that are too clicky). I may listen to some of those bands and enjoy them for their creativity and skill, but I don't view them from the lens of being death metal.