I like Serpents of the Light actually, mostly because I am amazed that a hybrid of black metal guitar style with death metal composition ends up sounding like Grindcore (or maybe like German band Blood), probably due to the way the vocals were created, at a very high and chanting level, almost like hardcore music.
This brings us to the problem of the album and that is that when the vocals are loud, you can decifer them, and like you said, God rapes blah blah blah over and over again sounding very near to Peter Steele gets pretty old fast. The doomish and symphonic guitar melodies keep bringing me back though, because they always resolve in an interesting way with the song structures, even though those structures are pretty basic.
Deicide is over all a solid band until their two crappy albums after Serpents, which Glan claims was done on purpose. I don't know about that, nor do I know if they did anything of merit after those albums came out, because I have never heard anything good said about their newer albums, and I didn't suspect they suddenly got better.