Following the disbandment of Hellion's legitimate straight edge youth crew band Die Hard, he morphed this vision into a real band, forming Integrity in 1988 with guitarist Aaron Melnick, who was also in Die Hard, as well as drummer Tony "Chubby Fresh" Pines and bassist Tom Front.

[1] In the following years, Hellion met Aaron Melnick while both working as road crew, and they shared over their similarly broad musical taste.

[2] Their second album They hired guitar Chris Smith, who was in the band False Hope, and Mark Konopka who was previously a member of Outface.

[10] In 1999, the Melnick brothers departed from the group, leading to Hellion hiring Dave and Steve Felton of Mushroomhead, as well as bassist Craig Martini.

[18] That same year, the band began recording with its Systems Overload era lineup: Hellion, Aaron and Leon Melnick, Chris Smith and Mark Konopka.

[25] Integrity have cited musical influences including G.I.S.M.,[27] Raw Power,[28] Max and Igor Cavalera of Sepultura and Cavalera Conspiracy,[29] Amebix,[30] Slayer,[23] Judge, Cro-Mags, Straight Ahead, Gorilla Biscuits, Underdog, Suicidal Tendencies, Negative Approach, Project X, Side by Side,[3] Whitehouse,[31] Danzig,[32] Randy Uchida Group, Sex Messiah, G.A.T.E.S., Zouo, LSD, Arkha Sva, Kriegshog, AVM, Zyanose, Rapes,[33] Alan Lomax, Howlin' Wolf,[34] Celtic Frost, Septic Death, Black Sabbath, Samhain, Metallica, Joy Division, Bauhaus and Throbbing Gristle.

[35] Additionally, they have cited non-musical influences including Arthur Rimbaud, Charles Manson, the Bible,[36] Francis Bacon, Tristan Tzara and André Breton.

[37] Criminal and cult leader Charles Manson is a common topic of the band's lyrics, whom Hellion described as "both a political prisoner and religious martyr.

Those Who Fear Tomorrow (1991) merged hardcore with apocalyptic lyrics and metal's guitar solos and chugging riffs to create one of the primeval albums in the genre.

[41][42] The term "holy terror" refers to the specific style of metalcore that Integrity helped to pioneer,[43] which is typified by soaring guitar leads,[44] gravelly vocals[45] and lyrics discussing western esotericism.

[47] Philip Trapp of Loudwire stated that Integrity "charted the course for metalcore to come", citing Dwid Hellion as one of the genre's most iconic vocalists.

[49] They have been cited as an influence by bands including All Pigs Must Die,[50] Clear,[51] Converge,[52] Full of Hell,[53] Hatebreed,[54] Killswitch Engage,[55] Overcast,[51] Pulling Teeth,[56] Ringworm,[57] Rise and Fall[58] and Unbroken.