I think their problem is that most death metal fans are scared off by their religious content. Personally I don't care about religious content (I love Stryper and Holy Soldier) but I don't like death metal, I go for the melodic bands as I'm more of a hard rock fan. I think if they wanted to be more popular, they have two choices. Either keep playing death metal but drop the preaching because apart from black metal freaks, death metal fans are least likely to accept Christian content in their music.... or lighten up their music and try to appeal to a more traditional metal audience who won't care as much if they are religious or not.