POSSIBLY it came as no surprise that Kim Ki-duk's 18th feature, Pietà (Cert. 18), won the 2012 Golden Lion Award at Venice, that most Catholic and venerable of film festivals. In many ways, the movie is an illustration of Pascal's notion that Jesus will be in agony until the end of time. There is certainly a great deal of agony for Pietà 's characters; something the South Korean director (not to be confused with an earlier filmmaker bearing the same name) chronicles graphically and unblinkingly.

Lee Kang-do (played by the television star Lee Jung-jin) is a ruthless debt-collector for a loan shark. Their scam is to lend money to vulnerable artisans in Seoul's back streets, having first got them to take out industrial-accident insurance. Any failure to repay the exorbitant interest results in Kang-do's crippling them in order to pocket the compensation money. He goes about his work without a shred of pity. Even so, one begins to wonder if this young thug is just as oppressed as those he terrorises. Rather than a means of exchange, money becomes an object of worship, defining all characters in the film and how their relationships are (often very cruelly) conducted.

The director says: "From great wars to trivial crimes today, I believe all of us living in this age are accomplices and sinners to such. As no one is free from a deity, I decided to name this film 'Pietà ' [Pity] in seeking God's mercy."

Kang-do is solitary, friendless, and without any family. At least, that seems to be the case until a well-dressed mysterious woman (Cho Min-soo) calls on him, claiming to be his mother. She begs his forgiveness for abandoning him at birth, and endures his brutal denials that she is the genuine article. Slowly, he responds to the persistent devotion that she shows him. Becoming emotionally dependent on the woman affects his ability to continue working in the same manner as before.

Just as one begins to see a happy ending in sight, the plot thickens. Mammon's worshippers don't give way that easily. A dead son is cradled by his loving mother, and pity abounds in unexpected ways.

Pietà, Kim Ki-duk says, is a cry that God may have mercy on us; for we seem to have little power of ourselves to help ourselves. It is, therefore, a pity that the central character is unconvincing as Mammon's avenging angel: a pretty boy so slightly built that it's hard to imagine him knocking the skin off a rice pudding, let alone intimidating his debtors. On the other hand, the mother is completely persuasive - a means of grace that redeems not only those she touches, but the film itself.

RUNNING alongside the closing credits of Machine Gun Preacher (out on DVD, Cert. 18) are shots of Sam Childers, the real-life minister on whom the film is based. Rhetorically, he asks: does it matter how you bring an abducted child home? He implies that his violent means of doing so are justified. Sadly, in all the previous couple of hours, this ethical question is given scant attention.

Marc Forster (A Quantum of Solace) cannot seem to make up his mind whether he is directing a James Bond movie or a biopic about someone akin to Paul Rusesabagina, who protected many Tutsi refugees, as shown in Hotel Rwanda. We watch Gerard Butler (Phantom of the Opera; 300), sickeningly convincing as Sam, starting with his prison release and further vicious crimes before a conversion experience. His Christianity clearly owes much to the love of his long-suffering wife (Michelle Monaghan), but we learn little of how Sam reaches the decisions he does about his born-again life.

What is interesting about watch- ing this film, however, is trying to discern which of Sam's characteristics that powered his underworld existence God is able to redeploy. A certain high-handedness, possibly justified by his Evangelical outlook, means that he gets things done, building a church and orphanage in the war zone of Sudan. He berates his congregation in Pennsylvania for good intentions rather than actions. Sam storms out of a lavish party given by a businessman who has given only a fraction of the $5000 donation he sought. In desperation, he reduces his own wife and daughter to near-poverty in serving his holy vision, by ransacking the family funds.

One begins to suspect that, no matter how much he claims a divine imperative for all this, there is an overriding need in him to redeem his misspent moments past, no matter what the cost to anyone else. Right to the end, his best friend and former partner-in-crime is asking whether God is going to forgive all the things that they have done.

The African scenes, though touching and horrific in equal measure, rarely give us much insight into the causes that the warring sides are fighting for. The Lord's Resistance Army do unspeakable things to thousands of children and adults, but we are not told why. Sam's gun-toting brand of Christianity hardly questions the means by which he delivers and then defends the goods. It is left to an English female doctor to point out that his methods and ideals have great similarity to those of Joseph Kony, the LRA leader.

By this stage of the film, the narrative is begging for some dramatic rupture to spice up our interest. Unlike, apparently, the actual person, film Sam undergoes a crisis of faith; so convinced had he been that the mind of God entirely coincided with his own world-view. It takes a previously traumatised boy to speak of the atrocities that he has witnessed to rouse the despondent protector. "If we allow ourselves to be full of hate, then they have won," the child tells him. "We must not let them take our hearts". There is not much evidence that Sam heeds this solidly Christian piece of advice.