"You can plug anything into that one really. Obviously “Halo On Fire,” there’s a juxtaposition in all of us, good, evil, and when does that come out, when does it show itself? Some people portray themselves as real saints, [and] the more their darkness is, the more they have to portray themselves as saints. So you’re basically getting away from the real “you,” like you’re making up for all of this [stuff] that you think is really bad. "
As James said it in the discussion in Metallica's blog, https://www.metallica.com/blog/so-what-article/436104/james-hetfield-the-hardwired-lyrics-discussion
"You can plug anything into that one really. Obviously “Halo On Fire,” there’s a juxtaposition in all of us, good, evil, and when does that come out, when does it show itself? Some people portray themselves as real saints, [and] the more their darkness is, the more they have to portray themselves as saints. So you’re basically getting away from the real “you,” like you’re making up for all of this [stuff] that you think is really bad. "