Bring Me the Horizon released "Mantra" as their first new material since That's the Spirit on 21 August 2018, the day before the band's sixth studio album Amo was announced.

[1] The song was originally teased with a promotional campaign including a billboard in London, which featured the lyric "Do you wanna start a cult with me?"

[12] Musically, "Mantra" is described by NME writer Tom Connick as featuring "a twisted, glitchy electronica intro" followed by a "festival-headline-baiting chorus", contributing to a sound that he claims is "built for huge stages".

[17] Tom Connick of the NME praised "Mantra" as "an inventive cut of ballsy, bluesy modern rock, fit for stadiums and headline slots", highlighting the electronic elements of the song and the vocal performance of Oliver Sykes.

[13] Axl Rosenberg of MetalSucks criticised the song, calling it "drek" and joking, "If you hate everyone in your immediate vicinity, turn your speakers way up and crank "Mantra".