Well , it's obvious the song is about whether one sees that there is life after death, an afterlife. It is very hard to tell whether Elvis is supporting the idea of life after death, but it seems like he wants us to think about it. I can see he also had an opportunity to use clever references to (what we turn into --dust) and other things. It almost appears to be written from a non-believers point of view. In the lines here come the juggernaut and poisoners and then comes
the lamb of god. These lines are there to make us think beyond what society tells. I am pretty confident Elvis is a believer, it is just a song to make us all think.