Mullen is a member of the band Suffocation. In an interview conducted by Doug Folden, Mullen was asked about his lyrics -- where they come from. He responded "Basically, a lot of it comes from my own thoughts. A lot of it has to do with government, the way we see it. It deals with a lot of stuff that's just the way we see the world and we see what's happening, is where a lot of our lyrics come from. I'm not really satanic, I don't really believe in that. I have my own religious views and stuff, I don't believe in [...] one or the other. So my religious views are on, I guess, an atheist point."