Ah, 1996. Green Day had already achieved some notoriety from 1994's Dookie album, and The Offspring had done the same with 1994's Smash. Both were hailed as breakthrough punk bands, and Slayer was none too happy about it. Specifically guitarists Kerry King and Jeff Hanneman, who felt they had to do something about the rash on un-punk "-punk" music that was coming out.
That "something" ended up being Undisputed Attitude, says King in a recent interview.
“I remember in particular when we did Undisputed Attitude in 1996, we did that in rebellion to Green Day and The Offspring. It’s not their fault but everyone called them punk bands and me and Jeff were, ‘This isn’t punk, guys.’ We just took offense to it and Undisputed Attitude was that coming out.”
In that same interview, King also puts down Slayer's 1998 album Diabolus In Musica, saying that's the album that made him realize how far Slayer had come from its original intent.
“For me especially, it took 1998’s ‘Diabolus In Musica‘ to come out and get past that and then say, ‘This ain’t what Slayer’s about, we gotta redefine and show everybody that Slayer’s still here and not trying to be somebody we’re not.’ I think that’s what ‘God Hates Us All‘ was.”
So… thanks Green Day and The Offspring, kind of.