[3][4] The album demonstrated singer and lyricist Martin Walkyier's deep held beliefs in Wyrdism, Anglo-Saxon spirituality, Celtic mysticism and paganism.

Musically the album reflected composer Andy Sneap's predilection at that time for increasingly lengthy and progressively technical thrash metal songs.

The album has come to be regarded as a classic of the thrash metal genre, described variously upon its re-release in 2007 as "essential listening" (Rock Sound), a "staggering work of total excellence" (Kerrang!

Speaking to Kerrang!, Walkyier explained that in "The Clerical Conspiracy", "the monks are talking in an abbey in the north of England, discussing the best way of converting Pagans in the south to Christianity.

"[3] Having accepted the quest, Wat Brand sets sail for the south of England, via the coast, and according to Martin Walkyier, "Advent of Insanity" depicts his thoughts during the journey, thinking about what he left behind and the perils that face him in the future… Did he do the right thing?

"[3] In "The Best of Enemies", the morning after his nightmare, Brand finally meets his guide, Wulf, who tells him of the pagan ways and starts to rebuke his Christian ideas.

describes Brand’s first real meeting with the spirits and makes plain their intention to fight for their survival notwithstanding the threat of their imminent replacement by Christianity.

The new edition features an expanded booket with extra photos and liner notes, remastered sound (undertaken by the band's own Andy Sneap), and three bonus live tracks, recorded in East Berlin in 1990: