However, Veniamin continues his protest, diving into the pool fully clothed and becoming increasingly disruptive in the classroom. A particular target for his righteous ire is his biology teacher Elena Lvovna (Victoria Isakova), whose lessons on sex education and evolution are predictably noxious to the new zealot. Vladimir Putin glowers in the background from the official state portrait as the school authorities try to contain the young man but in doing so it is Elena who becomes the target of official disapproval. Maybe she should try to compromise with Venya; perhaps she is as fundamental as he is. The Orthodox priest Father Vselod (Nikolai Roshin) is also called in to mediate and he is gleefully welcoming of Venya's enthusiasm even as he tries to steer it into the church's own path.
The true origins of Venya's faith are never fully unpicked, perhaps because they can't be. There is sexual confusion and repression certainly. He is attracted to a fellow student (Aleksandra Revenko) who teases and flirts with him alternately. He also befriends the much bullied disabled boy Grigoriy (Aleksandr Gorchilin) who he needs to try some faith healing out on and who is obviously besotted by his new friend. But Venya's religious ardour is deeply rooted and he quotes The Bible throughout and extensively, selecting the most extreme and uncomfortable texts. "Other religions have suicide bombers, why don't we?" he tells the priest. Meanwhile, Elena becomes similarly obsessed, studying scripture for "loopholes" as W.C. Fields might have put it and become increasingly unnerved in her isolation.
The school itself is seen as overly tolerant of Venya's intolerance and there is a latent religious faith simmering beneath the surface of Russian society that invisibly strengthens the young man's hand in the struggle that soon boils down to the student and his science teacher and when Venya's vitriol turns homophobic and anti-Semitic this also seems to chime with prejudices already in place, if usually unexpressed. Although its theatrical origins can be seen in some of the overly didactic poses that the characters bend and twist into, Serebrennikov has an eye for the late summer light and moves his camera confidently through the scenes in precise long takes.
The gimmick of placing chapter and verse on the screen every time The Bible is cited makes the important point that the text says a lot of mad things and can be used to justify the most toxic and disgusting ideas, but it also becomes distracting to the eye when so much more is taking place. However, this is a quibble for what is a powerful parable on the dangers and attractions of extremism. Vanya constantly carries his Bible, a little black book that is not actually that dissimilar from Mao's Communist totem. As Communism once filled a God-shaped hole, The Student warns that religious extremism could fill a communism-shaped hole. Ultimately, it is all to do with totalitarian longings.
The 69th Cannes Film Festival takes place from 11-22 May 2016. Follow our coverage here.
John Bleasdale | @drjonty