Unlike Behemoth's previous studio albums, the piano and a horn section (a trio of trumpet, trombone, French horn) were used in several of the album's songs. During the recording sessions, the band re-recorded a new version of "Chant for Eschaton 2000" – originally released on their album Satanica – which was released on the band's 2008 EP, Ezkaton. The Apostasy is Behemoth's first album to chart on the Billboard 200, having debuted at #149. The album was also put out in vinyl format limited to 500 copies.
The album title refers to "apostasy", the state of having forsaken one's professed belief set, often in favour of opposing beliefs or causes. The album cover artwork is a depiction of the Hindu goddess Kali.
"Rome 64 C.E." – the Great Fire of Rome occurred in 64 C.E., in which Peter from the bible (and possible other apostles as well), were allegedly killed. This explains the name of the song "Slaying the Prophets ov Isa".
"Slaying the Prophets ov Isa" – Isa is the Arabic name for Jesus.
"Pazuzu" – the Pazuzu was a much-feared creature of legend in Mesopotamian mythology, with a deformed head, wings of an eagle, sharp claws of a lion on its feet, and tail of a scorpion. It is the personification of the south-east storm wind, which brings diseases.
"Christgrinding Avenue" talks about the Via Dolorosa and the crucifixion of Jesus.