Killswitch Engage is considered a metalcore band. Like some 2000s metalcore bands, Killswitch Engage vocally combine singing, screaming vocals, and growls in their music. In 2009, MTV, while naming "The Greatest Metal Bands of All Time", said that Killswitch Engage have been "called one of the founders of metalcore". Jason D. Taylor of Allmusic said "Alive or Just Breathing" is "a pure metal album that seemingly has ignored any fashionable trend and instead relies solely on skill and expertise to sculpt some of the meatiest heavy metal since the glory days of Metallica and Slayer." Both current vocalist Jesse Leach and former vocalist Howard Jones write lyrics that are considered positive. Jesse Leach stated on "(Set This) World Ablaze", that the lyrics contain "unity, positivity, love." On the lyrical themes of "Killswitch Engage", Ultimate Guitar reviewer Amy Sciarretto notes: