Sean Gilman’s review published on Letterboxd :
When I wrote about this, Lau Kar-leung's directorial debut, last year, I focused mostly on the prologue as an encapsulation of what would become Lau's project as a director (as it had been as a choreographer), that of bringing historical verisimilitude to the martial arts film. I neglected the main body of the film, and that was a mistake, for it further complicates this idea, both meta-cinematically (the hero is a performer, using stage tricks to make his fighting seem more impressive than it really is: fake swords, fireproof ointments) and metaphysically (riffing on the title of the film and its related martial art: what does it mean to be a spiritual boxer? The hero claims to be literally possessed by spirits of past heroes (is that any different from an actor playing the role of such a hero?), and he never doubts that these spirits are real. Though he knows he and his master use special effects in order to gull the credulous, in his mind that doesn't delegitimize the Taoist mythology they're exploiting, it just makes them cheats. At one point, in the middle of the film, he himself is tricked into believing he has magical powers.
But in a less literal sense, the hero is a spiritual boxer in that his actions bring him into line with the moral aims of his religious tradition. Set adrift when his master gets drunk and disappears, Siu uses his powers (real and phony) not to steal from people, but to protect the weak from the predations of the strong. Moreover, he does do so not out of some stiff preachiness, but simply because it's naturally the right thing to do. One can see here the imperative of the 36th Chamber: to go out into the world and do good for the people as the highest spiritual good, not bells and whistles, temples and sacraments, mythology and dogma. Lau may poke fun and priests and religions, but it is the prodding of a true believer.