Bad Religion is an American punk rock band that formed in Los Angeles​, California in 1980. The band's lyrics cover topics related to religion, politics, society, the media and science. Musically, they are noted for their melodic sensibilities and extensive use of three-part vocal harmonies. The band has experienced multiple line-up changes, with singer Greg Graffin being the band's only constant member, though fellow founding members Jay Bentley and Brett Gurewitz have since rejoined, and guitarist Brian Baker has performed with the group since 1994. The most recent additions to the band are guitarist Mike Dimkich and drummer Jamie Miller, who joined in 2013 and 2015 respectively. To date, Bad Religion has released seventeen studio albums, two live albums, three compilation albums, three EPs, and two live DVDs. They are considered to be one of the best-selling punk rock acts of all time, having sold over five million albums worldwide.

After gaining a large underground following and critical praise through their releases on Gurewitz's label Epitaph in the 1980s and early 1990s, Bad Religion experienced mainstream success after signing to the major label Atlantic in 1993, and along with California-based bands like Green Day, The Offspring, NOFX and Rancid, they were responsible for the punk rock revival movement of the 1990s. Their seventh studio album and Atlantic debut, Recipe for Hate (1993), peaked at number 14 on Billboard's Heatseekers chart, and spawned one of their most popular songs "American Jesus". The band's 1994 follow-up Stranger than Fiction was also very successful, and included the hit singles "Infected", "Stranger than Fiction" and the re-recorded version of "21st Century (Digital Boy)"; the album was later certified gold, both in the United States and Canada.

Shortly before the release of Stranger than Fiction, Gurewitz left Bad Religion to run his label Epitaph on a full-time basis (in response to the success of the label's then-artists the Offspring and Rancid), and was replaced by Brian Baker. The band's success had slowly dwindled by the late 1990s, and after three more albums, they were dropped from Atlantic in 2001; this resulted in Bad Religion returning to Epitaph and Gurewitz rejoining the band. Since then, they have undergone a resurgence in popularity, with "Sorrow", "Los Angeles Is Burning" and "The Devil in Stitches" being Top 40 hits on the US charts, and their sixteenth studio album True North (2013) becoming Bad Religion's first album to crack the top 20 on the Billboard 200 chart, where it peaked at number 19. The band's seventeenth and most recent studio album, Age of Unreason, was released on May 3, 2019, and a follow-up album is reportedly in the works.