Eric's look hasn't really changed much in the past 17 or so years of Saviour Machine (except for certain accessories or his jewel on his forehead) the reason Eric wears it is it symbolically, to represent the seal of the Lamb, spoken of in Revelation; plus Eric just thought it looked cool

most of Saviour Machine's theatrics are symbolic in their nature and meaning, Eric drapes the American flag over his shoulders whenever he sings the song Legion in concert to represent the reason why it was banned (and their first album) in the US. He burns the UN flag (yes) to symbolically (not literally) show the New World Order (he's said in an interview he holds nothing against the UN but as a symbol of the New World Order spoken of in Revelation, there was no other flag or symbol to do the job lol). There is one more interview (or atleast a snippet of) explaining why the theatrics in the first place.
"With the whole persona of Saviour Machine, we’ve been ridiculed by really conservative groups. I think this is one of the biggest problems we have in the U.S.: ‘How can they look like that? How can they be Christians?’ And what’s funny is we took this metaphor right up in concert. The mask itself has always been a representative metaphor of the flesh, and how quickly people judge flesh, instead of what’s beneath it. A great deal of time and thought went into coming up with this original look, this original feel and concept. And it all has relevance. It all has purpose. My makeup has always represented the mask itself. And it just shows very clearly how quickly people judge a book by its cover. There are a lot of people out there that still can’t see past, or see beyond the horizon, and see what lies behind the mask. If people could just stop judging a book by its cover and seek what’s within, we might be able to step closer to the truth."
[ame="http://www.youtube.com/watch?v=CLZVHg5GhZ8"]YouTube - Saviour Machine - The Beast[/ame] (The Beast)
[ame="http://www.youtube.com/watch?v=5bi7R8-hXoQ&feature=related"]YouTube - Saviour Machine- The Lamb[/ame] (Legend I:I/The Lamb)
One thing I find truely amazing is the band's ability to shift the mood from oppressive and dark to one of glorious and magnificent; as demonstrated by these two songs; the first is the second part of "Legend I:II abridged into The Beast" and its counterpart Legend I:I abridged into The Lamb". The songs reflect both the rise of the Antichrist and the reign of the Lamb.