Rivers of Heresy

Vennart stated that his approach was to "mak[e] the most fucking poisonous vile music [he] possibly could, just unabridged hatred in musical form", while Simon Neil called it "lyrically [...] as misanthropic and nihilistic as [he's] ever written".[3] The project was initially stated to be a grindcore project, with a writer for Metal Injection finding the final result to be of varying styles of heavy metal instead.[4]

Professional ratings

Aggregate scores
Source	Rating
Metacritic	69/100[2]
Review scores
Source	Rating
Kerrang!	4/5[5]
The Line of Best Fit	7/10[6]
Mojo	[7]
NME	[8]
The Skinny	[9]

Rivers of Heresy received a score of 69 out of 100 on review aggregator Metacritic based on five critics' reviews, indicating "generally favorable" reception.[2] Mojo wrote that "Empire State Bastard make you feel like you've been in a cage fight with Mike Tyson".[7] James Hickie of Kerrang! remarked that the album "manages to surprise by bringing out lesser seen sides of its creators", as Vennart "has long showcased a songwriter of craftsmanship and nuance, so it's startling to hear him being so unremittingly brash here. As it is to find Simon, no stranger to moments of righteous indignation in Biffy, letting rip in larger, scarier increments".[5]

Andrew Trendell of NME thought the album "too hard for most Biffy fans and not pure enough for many Slayer faithful, but it's its own wonderfully weird wee beast. These are the sharper edges that Neil let out on Biffy's earlier work, but elevated that the pure ultraviolence of Vennart's songwriting and madcap riffery".[8] The Line of Best Fit's Elliot Burr stated that "the mathy and shouty post-hardcore of Neil's early noughties output turns its intentionally ugly head once again on the aptly dubbed Rivers of Heresy", which "flourishes when it veers into heady atmospherics".[6] Joe Goggins of The Skinny described it as "punishingly loud, often furiously paced, and has Neil vocally channeling Chino Moreno as he flits between screaming and singing. When it works, it's thrilling, especially on the moody 'Moi' and the mercurial, atmospheric 'Sons and Daughters'".[9]

Empire State Bastard

• Simon Neil – lead vocals, guitars
• Mike Vennart – guitars

Additional personnel

• Dave Lombardo – drums
• Naomi Macleod – bass

Production

• Adam Noble – production
• Tom Peters – recording