The film reads like a continuation of Empties. The protagonist (a writer here, while in Empties he's a teacher on self-imposed retirement) is half-dead, clinging to life via a sexual addiction - a Peter Pan complex of sorts. Perfect emancipatory words are uttered by the character of Vendula, a vibrant young woman. The old writer, same as the old teacher, is obsessed with young women whom he necessarily wants to "conquer". While the teacher in Empties tries (at least ostensibly) to revive his marriage, in Bethlehem Light he invents a young "macho" alter-ego to carry out the fantasy.
Tormented by repressed guilt, the writer Karel convicts himself, literally ending up in jail, through the character Matej. There are powerful metaphors: e.g. The iron balls of the prisoner; and the iron which covers Vendula's private parts in a photograph (Matej is image-obsessed, an erotic photographer). An iron is supposedly hot, but looks like a chastity belt on the woman whom the writer seduces through the false self (a "charismatic shooter" Sagittarius type, as expressed). His declaration of freedom is in fact a prison, an inability to have real intimacy, having objectified the woman. While in Empties there may have been redeeming qualities to the protagonist, in Bethlehem Light it is clear that marital bliss was an illusion, the woman sacrificing herself for nothing, or for the "empty" that is indeed her husband (she should have eloped with her suitor); the iron loses erotic connotation and becomes an object of tedious utility. The wife is conscious she is only there to iron and wash for the man, incapable of either igniting or purifying him. The protagonist could never change, and he only romanced her for his own convenience - a figure enabling him to emulate a normal life while he chased young women. While psychologically dependent on her, he only feels anything for her through jealously (the same in BL and in Empties). While in Empties the wife still nurtures hopes and illusions, in BL she is entirely stripped of them, the life drained from her; she cannot even have a private moment to play music due to her self-obsessed husband's perpetual presence-absence. Maybe it is in her dreams that he is dying.
In the scenes with the loving family with disabled son, there's the spiritual poignancy, a sudden warm elation which the director had also conveyed in Kolja.
Pure love, undoubtedly, does exist.
