The album generally received rave reviews from music critics. Allmusic critic Gregory Heaney praised the album, writing that it "rewards repeat listens with new surprises, giving anyone with the fortitude to wade through the muck and sludge even more glimpses at the warm, shoegaze center that lives at the heart of this doomy juggernaut." Iann Robinson of CraveOnline awarded the album with a perfect score, stating: "Heathen leaves you breathless, stammering for a way to process everything you’ve just heard." Robinson also added that the band "are able to translate the darkest parts of the human soul into music, and for that we should all be grateful."Pitchfork's Kim Kelly described the album as "a portrait of a band that is in complete harmony with itself, if not the world it inhabits." Michael Nelson of Stereogum regarded the record as "a dark, bombastic, hugely ambitious album of great sorrow, but perhaps even greater beauty," while Spin magazine described it as "the culmination of all that perspiration, almost cinematic in the scope of the suffering and seething anger it portrays."The Quietus' Robin Smith thought the record as "doom metal siren song – its beauty is incidental to a forever kind of pain."